Omicron Variant
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Omicron (B.1.1.529) is a variant of SARS-CoV-2 first reported to the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
(WHO) by the Network for Genomics Surveillance in South Africa on 24 November 2021. It was first detected in
Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...
and has spread to become the predominant variant in circulation around the world. Following the original BA.1 variant, several subvariants of Omicron have emerged: BA.2, BA.3,
BA.4 Omicron (B.1.1.529) is a variant of SARS-CoV-2 first reported to the World Health Organization (WHO) by the Network for Genomics Surveillance in South Africa on 24 November 2021. It was first detected in Botswana and has spread to become the ...
, and
BA.5 Omicron (B.1.1.529) is a variant of SARS-CoV-2 first reported to the World Health Organization (WHO) by the Network for Genomics Surveillance in South Africa on 24 November 2021. It was first detected in Botswana and has spread to become the ...
. Since October 2022, two subvariants of BA.5 named BQ.1 and BQ.1.1 have spread rapidly. Three doses of a
COVID-19 vaccine A COVID19 vaccine is a vaccine intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2), the virus that causes coronavirus disease 2019 ( COVID19). Prior to the COVID19 pandemic, an e ...
provide protection against severe disease and hospitalisation caused by BA.1 and BA.2. The immunity effects of BA.2 are similar to those of BA.1. For three-dose vaccinated individuals, the BA.4 and BA.5 variants are more infectious than previous subvariants, making it likely, , for a new peak in COVID-19 infections to occur. __TOC__


Classification

On 26 November, the
WHO Who or WHO may refer to: * Who (pronoun), an interrogative or relative pronoun * Who?, one of the Five Ws in journalism * World Health Organization Arts and entertainment Fictional characters * Who, a creature in the Dr. Seuss book '' Horton He ...
's Technical Advisory Group on SARS-CoV-2 Virus Evolution declared PANGO lineage B.1.1.529 a variant of concern and designated it with the
Greek letter The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BCE. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as w ...
omicron Omicron (; uppercase Ο, lowercase ο, ell, όμικρον) is the 15th letter of the Greek alphabet. This letter is derived from the Phoenician letter ayin: . In classical Greek, omicron represented the close-mid back rounded vowel in contras ...
. The WHO skipped the preceding letters nu and xi in the
Greek alphabet The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BCE. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as we ...
to avoid confusion with the similarities of the English word "new" and the Chinese surname Xi. The name of the variant has occasionally been mistaken as "Omnicron" among some English speakers, due to a lack of familiarity with the
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
alphabet, and the relative frequency of the
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
prefix " omni" in other common speech. The
GISAID GISAID (Global Initiative on Sharing Avian Influenza Data) is a global science initiative and primary source established in 2008 that provides open access to genomic data of influenza viruses and the coronavirus responsible for the COVID-19 pan ...
project has assigned it the
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
identifier GR/484A, and the
Nextstrain Nextstrain is a collaboration between researchers in Seattle, United States and Basel, Switzerland which provides a collection of open-source tools for visualising the genetics behind the spread of viral outbreaks. Its aim is to support public he ...
project has assigned it the clade identifiers 21K and 21L, both belonging to a larger Omicron group 21M.


History

Omicron was first detected on 22 November 2021 in laboratories in
Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...
and
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
based on samples collected on 11–16 November, with the first known samples collected in
Johannesburg Johannesburg ( , , ; Zulu and xh, eGoli ), colloquially known as Jozi, Joburg, or "The City of Gold", is the largest city in South Africa, classified as a megacity, and is one of the 100 largest urban areas in the world. According to Demo ...
,
South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
on 8 November 2021. The first known cases outside of South Africa were two people who travelled on 11 November: one who flew from South Africa to
Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China ( abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delt ...
via
Qatar Qatar (, ; ar, قطر, Qaṭar ; local vernacular pronunciation: ), officially the State of Qatar,) is a country in Western Asia. It occupies the Qatar Peninsula on the northeastern coast of the Arabian Peninsula in the Middle East; it sh ...
, and another who travelled from
Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...
to
Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...
via
Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
. On 26 November 2021, WHO designated B.1.1.529 as a
variant of concern The term variant of concern (VOC) for SARS-CoV-2, which causes COVID-19, is a category used for variants of the virus where mutations in their spike protein receptor binding domain (RBD) substantially increase binding affinity (e.g., N501Y) in ...
and named it "Omicron", after the fifteenth letter in the Greek alphabet. As of 6 January 2022, the variant had been confirmed in 149 countries.


Origin hypotheses

Omicron did not evolve from any other variant, but instead diverged on a distinct track, perhaps in mid-2020. Competing hypotheses are being examined. One origin hypothesis is that various mutations in the Omicron variant, comprising a 9-
nucleotide Nucleotides are organic molecules consisting of a nucleoside and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules wi ...
sequence, may have been acquired from another coronavirus (known as HCoV-229E), responsible for the common cold. This is not entirely at times, viruses within the body acquire and swap segments of genetic material from each other, and this is one common means of mutation. A link with
HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...
infection may explain a large number of mutations in the sequence of the Omicron variant. Indeed, in order to be affected by such a high number of mutations, the virus must have been able to evolve a long time without killing its host, which can occur in people with a
weakened immune system Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...
who receive enough medical care to survive. This is the case in HIV patients in South Africa, who represent about 14% of the population (as of 2017). HIV prevention could be key to reducing the risk of uncontrolled HIV driving the emergence of
SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus that causes COVID-19 (coronavirus disease 2019), the respiratory illness responsible for the ongoing COVID-19 pandemic. The virus previously had a ...
variants. One hypothesis to explain the novel mutations is that
SARS-CoV-2 Severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus that causes COVID-19 (coronavirus disease 2019), the respiratory illness responsible for the ongoing COVID-19 pandemic. The virus previously had a ...
was transmitted from humans to mice and mutated in a population of
mice A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...
sometime between mid-2020 and late 2021 before reinfecting humans. On 1 December 2022, a team of researchers from the
Charité The Charité – Universitätsmedizin Berlin (Charité – Berlin University of Medicine) is one of Europe's largest university hospitals, affiliated with Humboldt University and Free University Berlin. With numerous Collaborative Research Cen ...
(Berlin) published a study in
Science (journal) ''Science'', also widely referred to as ''Science Magazine'', is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, ...
that claimed that "data revealed genetically diverse Omicron ancestors already existed across Africa by August 2021". After a re-analysis because of doubts, the team has retracted the article on 20 December 2022 due to contamination of the samples.


Spread

On 24 November 2021, the variant was first reported to the WHO from South Africa based on samples that had been collected from 14 to 16 November. South African scientists were first alerted by samples from the very beginning of November where the PCR tests had S gene target failure (occurs in a few variants, but not in Delta which dominated in the country in October) and by a sudden increase of COVID-19 cases in Gauteng; sequencing revealed that more than 70 percent of samples collected in the province between 14 and 23 November were a new variant. The first confirmed specimens of Omicron were collected on 8 November 2021 in South Africa and on 9 November in Botswana. Likely Omicron (SGTF) samples had occurred on 4 November 2021 in Pretoria, South Africa. When WHO was alerted on 24 November, Hong Kong was the only place outside Africa that had confirmed a case of Omicron; one person who traveled from South Africa on 11 November, and another traveler who was cross-infected by this case while staying in the same quarantine hotel. On 25 November, one confirmed case was identified in
Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...
from a traveler returning from Malawi, along with two who returned from South Africa and one from Madagascar. All four initial cases reported from Botswana occurred among fully vaccinated individuals. On 26 November, Belgium confirmed its first case; an unvaccinated person who had travelled from Egypt via Turkey on 11 November. All three initial confirmed and suspected cases reported from Israel occurred among fully vaccinated individuals, as did a single suspected case in Germany. On 27 November, two cases were detected in the United Kingdom, another two in
Munich Munich ( ; german: München ; bar, Minga ) is the capital and most populous city of the States of Germany, German state of Bavaria. With a population of 1,558,395 inhabitants as of 31 July 2020, it is the List of cities in Germany by popu ...
, Germany and one in
Milan Milan ( , , Lombard: ; it, Milano ) is a city in northern Italy, capital of Lombardy, and the second-most populous city proper in Italy after Rome. The city proper has a population of about 1.4 million, while its metropolitan city h ...
, Italy. On 28 November, 13 cases were confirmed in the Netherlands among the 624 airline passengers who arrived from South Africa on 26 November. Confirmation of a further 5 cases among these passengers followed later. Entry into the Netherlands generally required having been vaccinated or PCR-tested, or having recovered. The passengers of these two flights had been tested upon arrival because of the newly imposed restrictions (which were set in place during their flight), after which 61 tested positive for SARS-CoV-2. A further two cases were detected in Australia. Both people landed in
Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...
the previous day, and travelled from southern Africa to
Sydney Airport Sydney Kingsford Smith Airport (colloquially Mascot Airport, Kingsford Smith Airport, or Sydney Airport; ; ) is an international airport in Sydney, Australia, located 8 km (5 mi) south of the Sydney central business district, in the ...
via
Doha Airport Hamad International Airport ( ar, مطار حمد الدولي, ') is an international airport in the State of Qatar, and the home of Qatar’s flag carrier airline, Qatar Airways. Located east of its capital, Doha, it replaced the nearby Doha ...
. The two people, who were fully vaccinated, entered isolation; 12 other travellers from southern Africa also entered quarantine for fourteen days, while about 260 other passengers and crew on the flight were directed to isolate. Two travellers from South Africa who landed in Denmark tested positive for COVID-19; it was confirmed on 28 November that both carried the Omicron variant. On the same day, Austria also confirmed its first Omicron case. A detected Omicron case was reported in the Czech Republic, from a traveler who spent time in Namibia. Canada also reported its first Omicron cases, with two from travelers from Nigeria, therefore becoming the first North American country to report an Omicron case. On 29 November, a positive case was recorded in Darwin, Australia. The person arrived in Darwin on a repatriation flight from Johannesburg, South Africa on 25 November, and was taken to a quarantine facility, where the positive test was recorded. Two more people who travelled to Sydney from southern Africa via Singapore tested positive. Portugal reported 13 Omicron cases, all of them members of a soccer club. Sweden also confirmed their first case on 29 November, as did Spain, when a traveler came from South Africa. On 30 November, the Netherlands reported that Omicron cases had been detected in two samples dating back as early as 19 November. A positive case was recorded in Sydney from a traveller who had visited southern Africa before travel restrictions were imposed, and was subsequently active in the community. Japan also confirmed its first case. Two Israeli doctors tested positive and entered isolation. Both of them had received three shots of the Pfizer vaccine prior to testing positive. In Brazil, three cases of the Omicron variant were confirmed in
São Paulo São Paulo (, ; Portuguese for 'Saint Paul') is the most populous city in Brazil, and is the capital of the state of São Paulo, the most populous and wealthiest Brazilian state, located in the country's Southeast Region. Listed by the GaWC a ...
. Another five are under suspicion. A person in
Leipzig Leipzig ( , ; Upper Saxon: ) is the most populous city in the German state of Saxony. Leipzig's population of 605,407 inhabitants (1.1 million in the larger urban zone) as of 2021 places the city as Germany's eighth most populous, as wel ...
, Germany with no travel history nor contact with travellers tested positive for Omicron. On 1 December, the Omicron variant was detected in three samples in Nigeria that had been collected from travelers from South Africa within the last week. On the same day, public health authorities in the United States announced the country's first confirmed Omicron case. A resident of
San Francisco San Francisco (; Spanish language, Spanish for "Francis of Assisi, Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the List of Ca ...
who had been vaccinated returned from South Africa on 22 November, began showing mild symptoms on 25 November and was confirmed to have a mild case of COVID-19 on 29 November. Ireland and South Korea also reported their first cases. South Korea reported its cases from five travelers arriving in South Korea from Nigeria. On 2 December, Dutch health authorities confirmed that all 14 passengers with confirmed Omicron infection on 26 November had been previously vaccinated. The same day, the
Norwegian Institute of Public Health The Norwegian Institute of Public Health (NIPH) (Norwegian: ''Folkehelseinstituttet''; FHI) is a Norwegian government agency and research institute, and is Norway's national public health institute. It is subordinate to the Ministry of Health and ...
confirmed that 50 attendees of a company Christmas party held at a restaurant in Norway's capital,
Oslo Oslo ( , , or ; sma, Oslove) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population of ...
, were infected with the Omicron variant. France has confirmed only 25 cases of the new Omicron variant but officials say the number could jump significantly in the coming weeks. By 6 December,
Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
confirmed its first case of the variant. The case was a South African student entering to study at a private university. In Namibia, 18 cases out of 19 positive COVID-19 samples that had been collected between 11 and 26 November were found to be Omicron, indicating a high level of prevalence in the country. Fiji also confirmed two positive cases of the variant. They travelled from Nigeria arriving in Fiji on November 25. On 9 December, Richard Mihigo, coordinator of the World Health Organisation's Immunisation and Vaccine Development Programme for Africa, announced that Africa accounted for 46% of reported cases of the Omicron variant globally. On 13 December, the first death of a person with Omicron was reported in the UK. On 16 December, New Zealand confirmed its first case of the Omicron variant, an individual who had traveled from Germany via Dubai. The first death of a person with Omicron was reported in Germany on 23 December and in Australia on 27 December. By Christmas 2021, the Omicron Strain became dominant in the US. On 3 January 2022, South Korea reported the first two deaths of people who tested positive
post mortem An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any dis ...
for Omicron. On 29 March 2022, Omicron subvariant BA.2 overtook BA.1 and became the dominant strain in the U.S. As of May 2022, BA.2.12.1 was spreading in the US and two new subvariants of Omicron named BA.4 and BA.5, first detected in January 2022, spread in South Africa. All 3 subvariants have spike protein mutations of L452 and elude immunity from prior BA1 infection.


Reactions


Vaccine producers

On 26 November 2021,
BioNTech BioNTech SE ( ; or short for Biopharmaceutical New Technologies) is a German biotechnology company based in Mainz that develops and manufactures active immunotherapies for patient-specific approaches to the treatment of diseases. It develops ...
said it would know in two weeks whether the current vaccine is effective against the variant and that an updated vaccine could be shipped in 100 days if necessary.
AstraZeneca AstraZeneca plc () is a British-Swedish multinational pharmaceutical and biotechnology company with its headquarters at the Cambridge Biomedical Campus in Cambridge, England. It has a portfolio of products for major diseases in areas includin ...
,
Moderna Moderna, Inc. ( ) is an American pharmaceutical and biotechnology company based in Cambridge, Massachusetts that focuses on RNA therapeutics, primarily mRNA vaccines. These vaccines use a copy of a molecule called messenger RNA (mRNA) to produ ...
and
Johnson & Johnson Johnson & Johnson (J&J) is an American multinational corporation founded in 1886 that develops medical devices, pharmaceuticals, and consumer packaged goods. Its common stock is a component of the Dow Jones Industrial Average and the company i ...
were also studying the variant's impact on the effectiveness of their vaccines. On the same day,
Novavax Novavax, Inc. is an American biotechnology company based in Gaithersburg, Maryland that develops vaccines to counter serious infectious diseases. Prior to 2020, company scientists developed experimental vaccines for influenza and respiratory s ...
stated that it was developing an updated vaccine requiring two doses for the Omicron variant, which the company expected to be ready for testing and manufacturing within a few weeks. On 29 November 2021, The
Gamaleya Institute The Gamaleya Research Institute of Epidemiology and Microbiology,russian: Национальный исследовательский центр эпидемиологии и микробиологии имени почётного академ ...
said that
Sputnik Light Sputnik Light (russian: Спутник Лайт, Sputnik Layt or Lajt) is a single dose COVID-19 vaccine developed by the Gamaleya Research Institute of Epidemiology and Microbiology. It consists of the first dose of the Sputnik V vaccine, w ...
should be effective against the variant, that it would begin adapting
Sputnik V Sputnik V (russian: Спутник V, the brand name from RDIF) or Gam-COVID-Vac (russian: Гам-КОВИД-Вак, the name under which it is legally registered and produced) is an adenovirus viral vector vaccine for COVID-19 developed by ...
, and that a modified version could be ready for mass production in 45 days.
Sinovac Sinovac Biotech Ltd. () is a Chinese biopharmaceutical company based in Haidian District, Beijing that focuses on the research, development, manufacture, and commercialization of vaccines that protect against human infectious diseases. The comp ...
said it could quickly mass-produce an inactivated vaccine against the variant and that it was monitoring studies and collecting samples of the variant to determine if a new vaccine is needed. On 7 December 2021, at a symposium in Brazil with its partner
Instituto Butantan Instituto Butantan (in modern Portuguese, Instituto Butantã, ) is a Brazilian biologic research center located in Butantã, in the western part of the city of São Paulo, Brazil. Instituto Butantan is a public institution affiliated with the S ...
, Sinovac said it would update its vaccine to the new variant and make it available in three months. On 2 December, the Finlay Institute was already developing a version of Soberana Plus against the variant. Pfizer hoped to have a vaccine targeted to immunize against Omicron ready by March 2022.


World Health Organization

On 26 November 2021, the WHO asked nations to enhance surveillance and sequencing efforts, submit complete genome sequences and associated metadata to a publicly available database, such as
GISAID GISAID (Global Initiative on Sharing Avian Influenza Data) is a global science initiative and primary source established in 2008 that provides open access to genomic data of influenza viruses and the coronavirus responsible for the COVID-19 pan ...
, report initial cases/clusters associated with virus-of-concern infection to WHO through the IHR mechanism, where capacity exists and in coordination with the international community, perform field investigations and laboratory assessments to improve understanding of the potential impacts of the virus of concern on COVID-19 epidemiology, severity, and the effectiveness of public health and social measures, diagnostic methods, immune responses, antibody neutralization, or other relevant characteristics. On 26 November 2021, WHO advised countries not to impose new restrictions on travel, instead recommending a "risk-based and scientific" approach to travel measures. On the same day, the
European Centre for Disease Prevention and Control The European Centre for Disease Prevention and Control (ECDC) is an agency of the European Union (EU) whose mission is to strengthen Europe's defences against infectious diseases. It covers a wide spectrum of activities, such as: surveillance, e ...
(ECDC) reported modeling indicating that strict travel restrictions would delay the variant's impact on European countries by two weeks, possibly allowing countries to prepare for it. As with other variants, the WHO recommended that people continue to keep enclosed spaces well ventilated, avoid crowding and close contact, wear well-fitting masks, clean hands frequently, and get vaccinated. On 29 November 2021, the WHO said cases and infections were expected among those vaccinated, albeit in a small and predictable proportion.


International response

After the WHO announcement, on the same day, several countries announced travel bans from southern Africa in response to the identification of the variant, including the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
, which banned travel from eight African countries, although as of 30 November 2011 it notably did not ban travel from any European countries, Israel, Canada, or Australia where cases were also detected at the time the bans were announced. Other countries that also implemented travel bans include Japan, Canada, the European Union, Israel, Australia, the United Kingdom, Singapore, Malaysia, Indonesia, Morocco, and New Zealand. On 26 November 2021 the
Brazilian Health Regulatory Agency Brazilian Health Regulatory Agency ( pt, Agência Nacional de Vigilância Sanitária, links=no, italics=yes, ''Anvisa'', literally National Health Surveillance Agency) is a regulatory body of the Brazilian government, created in 1999 during Presi ...
recommended flight restrictions regarding the new variant. The
state of New York New York, officially the State of New York, is a state in the Northeastern United States. It is often called New York State to distinguish it from its largest city, New York City. With a total area of , New York is the 27th-largest U.S. state ...
declared a state of emergency ahead of a potential Omicron spike, although no cases had yet been detected in the state or the rest of the United States. On 27 November 2021, Switzerland introduced obligatory tests and quarantine for all visitors arriving from countries where the variant was detected, which originally included Belgium and Israel. On 26 November 2021 South African
Minister of Health A health minister is the member of a country's government typically responsible for protecting and promoting public health and providing welfare and other social security services. Some governments have separate ministers for mental health. Coun ...
Joe Phaahla defended his country's handling of the pandemic and said that travel bans went against the "norms and standards" of the World Health Organization. Some speculated that travel bans could have a significant impact on South Africa's economy by limiting tourism and could lead to other countries with economies that are reliant on tourism to hide the discovery of new variants of concern. Low vaccine coverage in less-developed nations could create opportunities for the emergence of new variants, and these nations also were struggling to gain intellectual property to develop and produce vaccines locally. At the same time,
inoculation Inoculation is the act of implanting a pathogen or other microorganism. It may refer to methods of artificially inducing immunity against various infectious diseases, or it may be used to describe the spreading of disease, as in "self-inoculati ...
had slowed in South Africa due to
vaccine hesitancy Vaccine hesitancy is a delay in acceptance, or refusal, of vaccines despite the availability of vaccine services and supporting evidence. The term covers refusals to vaccinate, delaying vaccines, accepting vaccines but remaining uncertain abou ...
and apathy, with a nationwide vaccination rate of only 35% as of November 24, 2021. On 29 November 2021, the WHO warned countries that the variant poses a very high global risk with severe consequences and that they should prepare by accelerating vaccination of high-priority groups and strengthening health systems. WHO director-general Tedros Adhanom described the global situation as dangerous and precarious and called for a new agreement on the handling of pandemics, as the current system disincentivizes countries from alerting others to threats that will inevitably land on their shores. CEPI CEO
Richard Hatchett Richard Hatchett is an American oncologist and epidemiologist who has been serving as chief executive officer of the Coalition for Epidemic Preparedness Innovations (CEPI) in Oslo and London since 2017. He was awarded the Secretary of Health and ...
said that the variant fulfilled predictions that transmission of the virus in low-vaccination areas would accelerate its evolution. In preparation for the Omicron variant arriving in the United States, President Joe Biden stated that the variant is "cause for concern, not panic", reiterated that the government was prepared for the variant and would have it under control and that large-scale lockdowns, similar to the ones in 2020 near the beginning of the pandemic, were "off the table for now." In mid-December 2021, multiple Canadian provinces reinstated restrictions on gatherings and events such as sports tournaments, and tightened enforcement of
proof of vaccination A vaccine passport or proof of vaccination is an immunity passport employed as a credential in countries and jurisdictions as part of efforts to control the COVID-19 pandemic via vaccination. A vaccine passport is typically issued by a governm ...
orders. British Columbia expressly prohibited any non-seated "organized New Year's Eve event", while Quebec announced a partial lockdown on 20 December 2021, ordering the closure of all bars, casinos, gyms, schools, and theatres, as well as imposing restrictions on the capacity and operating hours of restaurants, and the prohibition of spectators at professional sporting events. On 18 December 2021, the Netherlands government announced a lockdown intended to prevent spread of the variant during the holiday period. In late December 2021, some countries shortened the typical six-month interval for a booster dose of the vaccine to prepare for a wave of Omicron, as two doses are not enough to stop the infection. UK, South Korea and Thailand reduced to three months; Belgium, four months; France, Singapore, Taiwan, Italy and Australia, five months. Finland reduced it to three months for risk groups. Other countries continued with a six-month booster schedule. While antibody levels begin to drop at four months, a longer interval usually allows time for the immune system's response to mature.


Market reactions

On 26 November 2021, worry about the potential economic impact of the Omicron variant led to a drop in global markets, including the worst drop of the
Dow Jones Industrial Average The Dow Jones Industrial Average (DJIA), Dow Jones, or simply the Dow (), is a stock market index of 30 prominent companies listed on stock exchanges in the United States. The DJIA is one of the oldest and most commonly followed equity inde ...
in 2021, led by travel-related stocks. The price of
Brent Crude Brent Crude may refer to any or all of the components of the Brent Complex, a physically and financially traded oil market based around the North Sea of Northwest Europe; colloquially, Brent Crude usually refers to the price of the ICE (Intercon ...
and
West Texas Intermediate West Texas Intermediate (WTI) is a grade or mix of crude oil; the term is also used to refer to the spot price, the futures price, or assessed price for that oil. In colloquial usage, WTI usually refers to the WTI Crude Oil futures contract tr ...
oil fell 10% and 11.7%, respectively
Cryptocurrency A cryptocurrency, crypto-currency, or crypto is a digital currency designed to work as a medium of exchange through a computer network that is not reliant on any central authority, such as a government or bank, to uphold or maintain it. It i ...
markets were also routed. and the
South African rand The South African rand, or simply the rand, ( sign: R; code: ZAR) is the official currency of the Southern African Common Monetary Area: South Africa, Namibia (alongside the Namibian dollar), Lesotho (alongside the Lesotho loti) and Eswatini ...
also hit an all-time low for 2021, trading at over 16 rand to the
dollar Dollar is the name of more than 20 currencies. They include the Australian dollar, Brunei dollar, Canadian dollar, Hong Kong dollar, Jamaican dollar, Liberian dollar, Namibian dollar, New Taiwan dollar, New Zealand dollar, Singapore dollar, U ...
, losing 6% of its value in November. In early December 2021,
Jerome Powell Jerome Hayden "Jay" Powell (born February 4, 1953) is an American attorney and investment banker who has served as the 16th chair of the Federal Reserve since 2018. After earning a degree in politics from Princeton University in 1975 and a Jur ...
, the
chairman of the Federal Reserve The chair of the Board of Governors of the Federal Reserve System is the head of the Federal Reserve, and is the active executive officer of the Federal Reserve Board of Governors, Board of Governors of the Federal Reserve System. The chair shal ...
, testified before the U.S. Senate Committee on Banking that "The recent rise in COVID-19 cases and the emergence of the Omicron variant pose downside risks to employment and economic activity and increased uncertainty for inflation."


Subvariants


BA.1

BA.1 is the original strain of the Omicron variant. As of June 2022, Omicron (BA.1) had many mutations, some of which have concerned scientists. As of June 2022, Omicron (BA.1) had about 50 mutations, which is more than any previous
SARS-CoV-2 variant There are many variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Some are believed, or have been stated, to be of particular importance due to their potenti ...
, 32 of which pertained to the spike protein, which most
vaccines A vaccine is a biological preparation that provides active acquired immunity The adaptive immune system, also known as the acquired immune system, is a subsystem of the immune system that is composed of specialized, systemic cells and pro ...
target to neutralise the virus. As of December 2021, many mutations were novel and not found in previous variants. As of April 2022 the variant was characterised by 30
amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...
changes, three small deletions, and one small insertion in the spike protein compared with the original virus, of which 15 are located in the receptor-binding domain (residues 319–541). As of December 2022 the virus carried a number of changes and deletions in other genomic regions, for example three mutations at the
furin Furin is a protease, a proteolytic enzyme that in humans and other animals is encoded by the ''FURIN'' gene. Some proteins are inactive when they are first synthesized, and must have sections removed in order to become active. Furin cleaves these s ...
cleavage site, which facilitates its transmission. Researchers have detected several subvariants of Omicron and new ones continue to emerge. There are 310 Pango lineages currently associated with the Omicron variant. The 'standard' sublineage is now referred to as BA.1 (or B.1.1.529.1), and the two other sublineages are known as BA.2 (or B.1.1.529.2) and BA.3 (or B.1.1.529.3). In mid-2022, BA.4 (or B.1.1.529.4) and BA.5 (or B.1.1.529.5) were detected in several countries. They share many mutations, but also significantly differ. In general, BA.1 and BA.2 share 32 mutations, but differ by 28. BA.1 has itself been divided in two, the original BA.1 and BA.1.1 (or B.1.1.529.1.1) where the main difference is that the latter has a R346K mutation. Standard PCR and
rapid Rapids are sections of a river where the river bed has a relatively steep gradient, causing an increase in water velocity and turbulence. Rapids are hydrological features between a ''run'' (a smoothly flowing part of a stream) and a ''cascade''. ...
tests continue to detect all Omicron subvariants as COVID-19, but further tests are necessary to distinguish the subvariants from each other and from other COVID-19 variants.


BA.2

A laboratory study on hamsters and mice in Japan published as a non-peer-reviewed preprint in mid-February 2022 suggested that BA.2, is not only more transmissible than BA.1, but may cause more severe disease. This was later disproven by a study in late-October 2022, that found BA.2 actually caused less severe disease relative to the original omicron variant (which in turn, caused less severe disease compared to the delta variant). Therapeutic monoclonal antibodies used to treat people infected with COVID-19 did not have much effect on BA.2, which was "almost completely resistant" to casirivimab and imdevimab, and 35 times more resistant to sotrovimab than the original BA.1 subvariant.


Affected countries and transmissibility

According to early research, BA.2 is roughly 30% to 60% more transmissible than BA.1. The first known sequence of BA.2 was in a sample from 15 November 2021. As of 17 January 2022, BA.2 had been detected in at least 40 countries and in all continents except Antarctica. By 31 January, it had been detected in at least 57 countries. In global samples collected from 4 February to 5 March and uploaded to
GISAID GISAID (Global Initiative on Sharing Avian Influenza Data) is a global science initiative and primary source established in 2008 that provides open access to genomic data of influenza viruses and the coronavirus responsible for the COVID-19 pan ...
, BA.2 accounted for c. 34%, compared to 41% for BA.1.1, 25% for BA.1 and less than 1% for BA.3. In a review two weeks later, covering 16 February to 17 March, BA.2 had become the most frequent. However, the data is geographically skewed due to sequencing rate and speed; for example, among the 205,000 COVID-19 sequences from March that had been uploaded to GISAID as of 22 March, United Kingdom and Denmark accounted for more than , and most of the remaining were from other European countries, Australia, Canada and the United States (altogether, 6,000 were from Africa, Asia and Latin America). Based on GISAID uploads, BA.1 peaked in early January 2022, after which it was overtaken by both BA.1.1 and BA.2. In North America, parts of Europe and parts of Asia, BA.1 was first outcompeted by BA.1.1. For example, in the United States, France and Japan, BA.1.1 became the dominant subvariant in January 2022. By late December 2021/early January 2022, BA.2 appeared to have become dominant in at least parts of India (already making up almost 80 percent in
Kolkata Kolkata (, or , ; also known as Calcutta , the official name until 2001) is the capital of the Indian state of West Bengal, on the eastern bank of the Hooghly River west of the border with Bangladesh. It is the primary business, comme ...
in late December 2021) and the Philippines, had become frequent in Scandinavia, South Africa and Singapore, and was showing signs of growth in Germany and the United Kingdom. In Japan, which has quarantine and detailed screening of all international travellers, as of 24 January, the vast majority of BA.2 had been detected in people that had arrived from India or the Philippines with cases going back at least to 1 December 2021 (far fewer BA.1 or other variants were detected among arrivals from the two countries in that period), but small numbers had also been detected in people arriving from other countries. In Denmark, the first BA.2 was in a sample collected on 5 December 2021 and extremely few were found in the directly following period. By week fifty (13–19 December) it had started to increase, with BA.2 being at around 2 percent of sequenced cases compared to 46 percent BA.1 (remaining Delta). The frequency of both Omicron subvariants continued to increase throughout the last half of December; in week fifty-two (27 December–2 January), BA.2 had reached 20 percent and BA.1 peaked at 72 percent. In January 2022, BA.1 began decreasing, whereas BA.2 continued its increase. By the second week (10–16 January) of 2022, the frequency of the two was almost equal, both being near 50 percent (around one percent was the rapidly disappearing Delta). In the following week, BA.2 became clearly dominant in Denmark with 65 percent of new cases being the BA.2 subvariant. Trends from the other Scandinavian countries, India, South Africa and the United Kingdom also showed that BA.2 was increasing in proportion to the original BA.1. In early February 2022, it had become the dominant subvariant in South Africa, in late February it had become dominant in Germany and in early March it had become dominant in the United Kingdom. In early March, BA.1.1 was still heavily dominant in the United States (having overtaken BA.1 in January), but BA.2 was increasing in frequency, later becoming dominant in the US by 29 March.


XE

A new BA.1–BA.2 recombinant isolated from the UK in January 2022, dubbed the "XE" recombinant, was found by the WHO to be potentially 10% more transmissible than BA.2, making it about 43% to 76% to more transmissible than BA.1, and making the XE recombinant the most contagious variant identified.


BA.2.12

There were two new BA.2 subvariants detected in the US state of
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...
, which are BA.2.12 (or B.1.1.529.2.12) and BA.2.12.1 (or B.1.1.529.2.12.1), both of which have a significant growth advantage of 23–27% over BA.2 and contributing to a rise in infections in central New York, centred on
Syracuse Syracuse may refer to: Places Italy *Syracuse, Sicily, or spelled as ''Siracusa'' *Province of Syracuse United States *Syracuse, New York **East Syracuse, New York **North Syracuse, New York *Syracuse, Indiana * Syracuse, Kansas *Syracuse, Miss ...
and
Lake Ontario Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north, west, and southwest by the Canadian province of Ontario, and on the south and east by the U.S. state of New York. The Canada–United States border sp ...
, which later became dominant by May 24 in the US.


BA.2.75 and BA.2.75.2

The subvariant BA.2.75 (or B.1.1.529.2.75, nicknamed ''Centaurus'' by the media), first detected in
India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
in May 2022, has been classified as variant under monitoring by the WHO. Additional newer mutations in this line (like BA.2.75.2 aka B.1.1.529.2.75.2 or ''Chiron'') may be capable of escape neutralizing antibodies.


XBB and XBB.1

XBB, a recombinant of the BA.2.10.1 and BA.2.75 sublineages, is an Omicron subvariant first detected in August 2022. Described as "immune-evasive", it has caused a small surge of cases in countries including
Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...
and
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
. On 20 October 2022, the chief scientist of the World Health Organization (WHO), Soumya Swaminathan, warned that the XBB subvariant of Omicron may cause infections in some countries while the severity of the new variants is not yet known. Early observations from Singapore indicated the possibility of XBB being less severe compared to the omicron BA.5 variant, with data from the first two weeks in October 2022 indicating that the XBB variant had a 30% lower hospitalisation risk. However, this could also be due to high levels of population immunity from vaccination and previous waves.


BA.3

The third Omicron sublineage, BA.3, is very rare. It has the same S-gene target failure (SGTF) deletion (Δ69-70) as BA.1.


BA.4 and BA.5

In April 2022, the WHO announced it was tracking the BA.4 and BA.5 subvariants with BA.4 having been detected in South Africa, Botswana, Denmark, Scotland and England. Early indications from data collected in South Africa suggested BA.4 and BA.5 have a significant growth advantage over BA.2, which by 12 May earned the status Variant of Concern by the European Centre for Disease Prevention and Control, and, by 20 May, by the
UK Health Security Agency The UK Health Security Agency (UKHSA) is a government agency in the United Kingdom, responsible since April 2021 for England-wide public health protection and infectious disease capability, and replacing Public Health England. It is an executiv ...
. BA.5 was dominant in
Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...
by 25 May, accounting for two-thirds of all new cases there. By 24 June, BA.4 and BA.5 together had become dominant variants in the UK and Germany. These two subvariants became dominant in the United States by 28 June. By late June, BA.5 became the dominant subvariant in
France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
, with 59% of new cases linked to it. On 10 May 2022, a case of a new subvariant BA.5.2.1 was reported in California. On 10 July, the city of Shanghai reported its first case of BA.5.2.1, in a man who had flown in from Uganda, sparking a new wave of testing. On 22 July, the province of Ontario, Canada announced that subvariant BA.5.2.1 overtook BA.2.12.1 as the main variant in circulation in Ontario around 2 July. Regeneron is reporting that BA.5.2.1 is the main variant in Australia, Belgium, Brunei, Greece and Iceland. The government of Canada is also reporting that in late June and July, of the travelers arriving by air who test positive for COVID-19, a substantial proportion are BA.5.2.1. BF.7 is a shortened version of the sub-variants full name, which is BA.5.2.1.7. This sub-variant is part of Omicron's BA.5 variant, which has the highest number of reported cases globally, accounting for 76.2% of all cases.


BQ.1 and BQ.1.1

Since October 2022, BQ.1 (or B.1.1.529.5.3.1.1.1.1.1, nicknamed ''Typhon'' by the media) and BQ.1.1 (or B.1.1.529.5.3.1.1.1.1.1.1, nicknamed ''Cerberus'') which are subvariants of BA.5 have been found. They have been more prevalent in France than any other European country, As of 17 November, 93% of sequences in France were Omicron sub-lineage BA.5 and among the BA.5 sub-lineages, BQ.1.1 continued to rise (32% vs 25% in the prior week). according to Nextclade even 55%. they were reported in the US to have become dominant, accounting for 44% of new infections, up from 33% the previous week. Early laboratory tests found that these subvariants were better at escaping first and booster vaccines than previous variants; however, no new treatments appeared to be in development. Virologist Andy Pekosz said that "the mutations have pretty much eliminated every single monoclonal antibody on the market right now in terms of their efficacy".


Transmission


In humans

In January 2022, William Schaffner, professor of infectious diseases at Vanderbilt University Medical Center, compared the contagiousness of the Omicron variant to that of the
measles Measles is a highly contagious infectious disease caused by measles virus. Symptoms usually develop 10–12 days after exposure to an infected person and last 7–10 days. Initial symptoms typically include fever, often greater than , cough, ...
.


Vaccinated

It was not known in November 2021 how Omicron would spread in populations with high levels of immunity or if it causes a milder or more severe disease. On 15 December 2021, Jenny Harries, head of the UK Health Security Agency, told a parliamentary committee that the
doubling time The doubling time is the time it takes for a population to double in size/value. It is applied to population growth, inflation, resource extraction, consumption of goods, compound interest, the volume of malignant tumours, and many other things th ...
of COVID-19 in most regions of the UK was now less than two days despite the country's high vaccination rate. She said that the Omicron variant of COVID-19 is "probably the most significant threat since the start of the pandemic", and that the number of cases in the next few days would be "quite staggering compared to the rate of growth that we've seen in cases for previous variants".


Natural immunity

Relating to naturally acquired immunity, Anne von Gottberg, an expert at the South African
National Institute for Communicable Diseases The National Institute for Communicable Diseases (NICD) is the national public health institute of South Africa, providing reference to microbiology, virology, epidemiology, surveillance and public health research to support the government's re ...
, believed at the beginning of December 2021 that immunity granted by previous variants would not protect against Omicron.


Vaccinated or natural immunity

A study suggests that mutations that promote
breakthrough infection A breakthrough infection is a case of illness in which a vaccinated individual becomes infected with the illness, because the vaccine has failed to provide complete immunity against the pathogen (currently only viruses). Breakthrough infections ha ...
s or antibody-resistance "like those in Omicron" could be a new mechanism for
viral evolution Viral evolution is a subfield of evolutionary biology and virology that is specifically concerned with the evolution of viruses. Viruses have short generation times, and many—in particular RNA viruses—have relatively high mutation rates (on the ...
success of SARS-CoV-2 and that such may become a dominating mechanism of its evolution. A
preprint In academic publishing, a preprint is a version of a scholarly or scientific paper that precedes formal peer review and publication in a peer-reviewed scholarly or scientific journal. The preprint may be available, often as a non-typeset versio ...
supports such an explanation of Omicron's spread, suggesting that it "primarily can be ascribed to the immune evasiveness rather than an inherent increase in the basic transmissibility". Studies showed the variant to escape the majority of existing SARS-CoV-2 neutralizing antibodies, including those in sera from vaccinated and convalescent individuals. Nevertheless, current vaccines are expected to protect against severe illness, hospitalizations, and deaths due to Omicron and, on an individual level, the Omicron variant is milder than earlier variants that evolved when the antibody/vaccination share was lower than it was when Omicron emerged. In contrast to other investigated variants, Omicron showed substantial, population-level, evasion of immunity from prior infection as well as a higher ability to evade immunity induced by vaccines.


In non-human animals

In February 2022, the first confirmed case infecting a wild animal was confirmed by researchers at
Pennsylvania State University The Pennsylvania State University (Penn State or PSU) is a Public university, public Commonwealth System of Higher Education, state-related Land-grant university, land-grant research university with campuses and facilities throughout Pennsylvan ...
in
white-tailed deer The white-tailed deer (''Odocoileus virginianus''), also known as the whitetail or Virginia deer, is a medium-sized deer native to North America, Central America, and South America as far south as Peru and Bolivia. It has also been introduced t ...
in
Staten Island Staten Island ( ) is a borough of New York City, coextensive with Richmond County, in the U.S. state of New York. Located in the city's southwest portion, the borough is separated from New Jersey by the Arthur Kill and the Kill Van Kull an ...
, N.Y.


Surfaces

Although
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission *** ...
via
fomite A fomite () or fomes () is any inanimate object that, when contaminated with or exposed to infectious agents (such as pathogenic bacteria, viruses or fungi), can transfer disease to a new host. Transfer of pathogens by fomites A fomite is any ina ...
s is rare, preliminary data indicate that the variant lasts for 194 hours on plastic surfaces and 21 hours on skin, compared with just 56 and 7 hours, respectively, for the original strain.


Vaccine effectiveness

Pfizer-BioNTech (BNT162b2) and Moderna (mRNA-1273) mRNA Vaccines offer less protection against the omicron variant. In January 2022, results from Israel suggested that a fourth dose is only partially effective against Omicron. Many cases of infection broke through, albeit "a bit less than in the control group", even though trial participants had higher antibody levels after the fourth dose.


BA.1

In December, studies, some of which using large nationwide datasets from either Israel and Denmark, found that vaccine effectiveness of multiple common two-dosed
COVID-19 vaccine A COVID19 vaccine is a vaccine intended to provide acquired immunity against severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2), the virus that causes coronavirus disease 2019 ( COVID19). Prior to the COVID19 pandemic, an e ...
s is substantially lower against the Omicron variant than for other common variants including the
Delta variant The Delta variant (B.1.617.2) was a variant of SARS-CoV-2, the virus that causes COVID-19. It was first detected in India in late 2020. The Delta variant was named on 31 May 2021 and had spread to over 179 countries by 22 November 2021. The ...
, and that a new (often a third) dose – a
booster dose A booster dose is an extra administration of a vaccine after an earlier (primer) dose. After initial immunization, a booster provides a re-exposure to the immunizing antigen. It is intended to increase immunity against that antigen back to protec ...
– is needed and effective, as it substantially reduces deaths from the disease compared to cohorts who received no booster but two doses. On 7 December 2021, preliminary results from a laboratory test conducted at the Africa Health Research Institute in Durban with 12 people who received the Pfizer-BioNTech vaccine found a 41-fold reduction in
neutralizing antibody A neutralizing antibody (NAb) is an antibody that defends a cell from a pathogen or infectious particle by neutralizing any effect it has biologically. Neutralization renders the particle no longer infectious or pathogenic. Neutralizing antibod ...
activity against the variant in some of the samples. This is a significant reduction, but it does not mean that the variant can escape vaccines completely, so vaccination with current vaccines is still recommended. Neutralizing antibody activity against the variant was greater in those fully vaccinated after being infected about a year earlier. Effectiveness estimates will likely change as more data is collected, as antibodies generated by vaccination vary widely between individuals and the sample was small. On 8 December 2021, Pfizer and BioNTech reported that preliminary data indicated that a third dose of the vaccine would provide a similar level of neutralizing antibodies against the variant as seen against other variants after two doses. On 10 December 2021, the
UK Health Security Agency The UK Health Security Agency (UKHSA) is a government agency in the United Kingdom, responsible since April 2021 for England-wide public health protection and infectious disease capability, and replacing Public Health England. It is an executiv ...
reported that early data indicated a 20- to 40-fold reduction in neutralizing activity for Omicron by sera from Pfizer 2-dose vaccinees relative to earlier strains and a 20-fold reduction relative to Delta. The reduction was greater in sera from AstraZeneca 2-dose vaccinees, falling below the detectable threshold. An mRNA booster dose produced a similar increase in neutralising activity regardless of the vaccine used for primary vaccination. After a booster dose (usually with an mRNA vaccine), vaccine effectiveness against symptomatic disease was at , and the effectiveness against severe disease was expected to be higher. Many of the mutations to the spike protein are present in other variants of concern and are related to increased infectivity and antibody evasion. Computational modeling suggests that the variant may also escape
cell-mediated immunity Cell-mediated immunity or cellular immunity is an immune response that does not involve antibodies. Rather, cell-mediated immunity is the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in ...
. Vaccines continue to be recommended for BA.1. Professor Paul Morgan, immunologist at
Cardiff University , latin_name = , image_name = Shield of the University of Cardiff.svg , image_size = 150px , caption = Coat of arms of Cardiff University , motto = cy, Gwirionedd, Undod a Chytgord , mottoeng = Truth, Unity and Concord , established = 1 ...
said, "I think a blunting rather than a complete loss f immunityis the most likely outcome. The virus can't possibly lose every single
epitope An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds. The p ...
on its surface, because if it did that spike protein couldn't work any more. So, while some of the antibodies and T cell clones made against earlier versions of the virus, or against the vaccines may not be effective, there will be others, which will remain effective. (...) If half, or two-thirds, or whatever it is, of the immune response is not going to be effective, and you're left with the residual half, then the more boosted that is the better." Professor
Francois Balloux Francois Balloux is the director of the UCL Genetics Institute, and a professor of computational biology at University College London. Early life and education Balloux earned a master's degree in 1996 and a doctorate in 2000 from the Universi ...
of the Genetics Institute at
University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public research university , endowment = £143 million (2020) , budget = ...
said, "From what we have learned so far, we can be fairly confident that – compared with other variants – Omicron tends to be better able to reinfect people who have been previously infected and received some protection against COVID-19. That is pretty clear and was anticipated from the mutational changes we have pinpointed in its protein structure. These make it more difficult for antibodies to neutralise the virus." On 23 December 2021, ''
Nature Nature, in the broadest sense, is the physics, physical world or universe. "Nature" can refer to the phenomenon, phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. ...
'' indicates that, though Omicron likely weakens vaccine protection, reasonable effectiveness against Omicron (BA.1) may be maintained with currently available vaccination and boosting approaches.


BA.4/5

In May 2022, a
preprint In academic publishing, a preprint is a version of a scholarly or scientific paper that precedes formal peer review and publication in a peer-reviewed scholarly or scientific journal. The preprint may be available, often as a non-typeset versio ...
indicated Omicron subvariants BA.4 and BA.5 could cause a large share of
COVID-19 Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was COVID-19 pandemic in Hubei, identified in Wuhan, China, in December ...
- reinfections, beyond the increase of reinfections caused by the Omicron lineage, even for people who were infected by Omicron BA.1 due to increases in immune evasion, especially for the unvaccinated. However, the observed escape of BA.4 and BA.5 from immunity by a BA.1 infection is more moderate than of BA.1 against studied prior cases of immunity (such as immunity from specific vaccines).
Immunity Immunity may refer to: Medicine * Immunity (medical), resistance of an organism to infection or disease * ''Immunity'' (journal), a scientific journal published by Cell Press Biology * Immune system Engineering * Radiofrequence immunity desc ...
from an Omicron infection for unvaccinated and previously uninfected was found to be weak "against non-Omicron variants", albeit at the time Omicron is, by a large margin, the dominant variant in sequenced human cases.


BQ.1 and BQ.1.1

Subvariants BQ.1 and BQ.1.1 were found in late 2022 to be better at escaping first and booster vaccines than previous variants, and "to have pretty much eliminated every single monoclonal antibody on the market right now in terms of their efficacy".


Vaccine adjustments

As of June 2022, researchers, health organizations and regulators are discussing, investigating (including with preliminary laboratory studies and trials) and partly recommending COVID-19 vaccine boosters that mix the original vaccine formulation with Omicron-adjusted parts – such as
spike protein In virology, a spike protein or peplomer protein is a protein that forms a large structure known as a spike or peplomer projecting from the surface of an enveloped virus. as cited in The proteins are usually glycoproteins that form dimers or ...
s of a specific Omicron subvariant – to better prepare the immune system to recognize a wide variety of variants amid substantial and ongoing immune evasion by Omicron.


Signs and symptoms

Loss of taste and smell seem to be uncommon compared to other strains. A unique reported symptom of the Omicron variant is
night sweats Night sweats, also referred to as nocturnal hyperhidrosis (Hyperhidrosis - a medical term for excessive sweating + nocturnal - night), is the repeated occurrence of excessive sweating during sleep. The person may or may not also perspire exces ...
, particularly with the BA.5 subvariant. A study performed between 1 and 7 December 2021 by the
Center for Disease Control The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...
found that: "The most commonly reported symptoms erecough, fatigue, and congestion or runny nose" making it difficult to distinguish from a less damaging variant or another virus. Research published in London on 25 December 2021 suggested the most frequent symptoms stated by users of the Zoe Covid app were "a runny nose, headaches, fatigue, sneezing and sore throats."Omicron's cold-like symptoms mean UK guidance 'needs urgent update'
''
The Guardian ''The Guardian'' is a British daily newspaper. It was founded in 1821 as ''The Manchester Guardian'', and changed its name in 1959. Along with its sister papers ''The Observer'' and ''The Guardian Weekly'', ''The Guardian'' is part of the Gu ...
''
A British omicron case-control observational study until March 2022 showed a reduction in odds of long COVID with the omicron variant versus the delta variant of 0·24–0·5 depending on age and time since vaccination.


Virulence

As of 28 November 2021 the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of h ...
stated that no information suggested that symptoms associated with Omicron were different from other variants, but it was not yet clear whether Omicron was more
virulent Virulence is a pathogen's or microorganism's ability to cause damage to a host. In most, especially in animal systems, virulence refers to the degree of damage caused by a microbe to its host. The pathogenicity of an organism—its ability to ca ...
, causing more severe disease. Increased rates of hospitalization in South Africa at the time could be due to a higher number of cases, rather than any specific feature. On 4 December 2021, the
South African Medical Research Council The South African Medical Research Council (SAMRC) is a para-statal medical research organisation in South Africa. The current president is professor Glenda Gray. The South African Medical Research Council was established in 1969 to act as an indep ...
reported that from 14 to 29 November 2021 at a hospital complex in
Tshwane The City of Tshwane Metropolitan Municipality (also known as the City of Tshwane) () is the metropolitan municipality that forms the local government of northern Gauteng Province, South Africa. The Metropolitan area is centred on the city of Pr ...
, inpatients were younger than in previous waves and the ICU and oxygen therapy rates were lower than in earlier waves, but observations were not definitive and subject to change over the following two weeks. in the week of 28 November 2021 excess deaths nearly doubled suggesting under-reporting, but the level was much lower than that seen in the second wave in mid-January 2021. On 12 December 2021, director-general of the World Health Organization
Tedros Adhanom Tedros Adhanom Ghebreyesus ( ti, ቴዎድሮስ አድሓኖም ገብረኢየሱስ, sometimes spelt ti, ቴድሮስ ኣድሓኖም ገብረየሱስ, label=none; born 3 March 1965) is an Ethiopian public health official, researcher, and ...
said that it was wrong for people to consider Omicron as mild, as high exposure to previous infections in South Africa was likely to affect the clinical course of the new infections. On 20 December 2021, a report by the
Imperial College COVID-19 Response Team The Imperial College COVID-19 Response Team is a group of experts from Imperial College London studying the COVID-19 pandemic and informing the government of the United Kingdom, and governments and public health agencies around the world. The te ...
, based on data from England, found that hospitalisation and asymptomatic infection indicators were not significantly associated with Omicron infection, suggesting at most limited changes in severity compared with Delta. On 22 December 2021, the team reported an about lower risk of a hospitalization requiring a stay of at least 1 night compared to the Delta variant, and that the data suggested that recipients of 2 doses of the Pfizer–BioNTech, the
Moderna Moderna, Inc. ( ) is an American pharmaceutical and biotechnology company based in Cambridge, Massachusetts that focuses on RNA therapeutics, primarily mRNA vaccines. These vaccines use a copy of a molecule called messenger RNA (mRNA) to produ ...
or the Oxford–AstraZeneca vaccine were substantially protected from hospitalization.


BA.1 and Delta differences

As of 6 January 2022, Omicron BA.1 multiplied around 70 times faster than the
Delta variant The Delta variant (B.1.617.2) was a variant of SARS-CoV-2, the virus that causes COVID-19. It was first detected in India in late 2020. The Delta variant was named on 31 May 2021 and had spread to over 179 countries by 22 November 2021. The ...
in the
bronchi A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. ...
(
lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
airways) but evidence suggested it is less severe than previous variants, especially compared to Delta, since it might be less able to penetrate deep lung tissue. As of January 2022, in southern California infections were 91 percent less fatal than the delta variant, with 51 percent less risk of hospitalization. However, the estimated difference in the intrinsic risk of hospitalization in England largely decreased to 0–30 percent, when reinfections were excluded.


BA.1 and BA.2 differences

As of 21 January 2022 the risk of hospitalization was the same in BA.1 and BA.2 based on reviews from Denmark, India, South Africa and the United Kingdom. Norwegian studies showed that the amount of virus in the upper airways was similar in those infected with BA.1 and BA.2. As of 22 February 2022 studies from Denmark and Qatar found that after an infection with BA.1, the vast majority of people were well-protected against a BA.2 infection, and that antibodies for BA.1 generally protect against BA.2. although it was unknown how long this protection would last. In Denmark, preliminary data found breakthrough rates in vaccinated people were similar to the breakthrough rates seen for BA.1. A January 2022 study by the
UK Health Security Agency The UK Health Security Agency (UKHSA) is a government agency in the United Kingdom, responsible since April 2021 for England-wide public health protection and infectious disease capability, and replacing Public Health England. It is an executiv ...
found that vaccines afforded similar levels of protection against symptomatic disease by BA.1 and BA.2, and in both it was considerably higher after two doses and a booster than two doses without booster, though because of the gradually waning effect of vaccines, further booster vaccination may later be necessary.


Diagnosis

As of November 2021, the chance of detecting an Omicron case particularly depended on a country's sequencing rate, with South Africa sequencing far more samples than any other country in Africa, but at a considerably lower rate than most Western nations. Furthermore, it could take up to two weeks to return a viral sequence in places with the technical capability, hence solid statistics on confirmed cases have lagged the actual situation.


PCR testing

In December 2021, the US FDA published guidelines on how
PCR test The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) t ...
s would be affected by Omicron. Tests that detect multiple gene targets were to continue to identify the testee as positive for COVID-19. S-gene dropout or target failure was proposed as a shorthand way of differentiating Omicron from Delta. besides sequencing and genotyping. As of December 2021, Denmark and Norway have regarded cases found by their variant qPCR test, which is relatively fast and checks several genes, as sufficient for counting it as Omicron, before full sequencing.


BA.1 and BA.2 differences

As of 7 December 2021 it was known that BA.2 -unlike Ba1- lacks the characteristic S-gene target failure (SGTF) causing deletion (Δ69-70), by which many
qPCR A real-time polymerase chain reaction (real-time PCR, or qPCR) is a laboratory technique of molecular biology based on the polymerase chain reaction (PCR). It monitors the amplification of a targeted DNA molecule during the PCR (i.e., in real ...
tests have been able to rapidly detect a case as an Omicron (or Alpha) variant, from the previously dominant
Delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...
variant. Thus, countries which primarily rely on SGTF for detection may overlook BA.2, and British authorities consider SGTF alone as insufficient for monitoring the spread of Omicron. This has resulted in it having been nicknamed 'Stealth Omicron', but because BA.2 still can be separated from other variants through normal full sequencing, or checks of certain other mutations, the nickname is not quite accurate. As of January 2022, some countries, such as Denmark and Japan, have been using a variant qPCR which tests for several mutations, including
L452R There are many variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Some are believed, or have been stated, to be of particular importance due to their potenti ...
. It can also distinguish Delta, which has L452R, and all Omicron subvariants, which do not have L452R. As Omicron became dominant and the Delta variant became rare in early 2022, the SGTF mutation that had made Delta and BA.2 similar in qPCR tests was found to be useful for separating BA.1 and BA.2 from each other.


Rapid antigen testing

In January 2022 the medicine and therapeutic regulatory agency
Therapeutic Goods Administration The Therapeutic Goods Administration (TGA) is the medicine and therapeutic regulatory agency of the Australian Government. As part of the Department of Health and Aged Care, the TGA regulates the quality, supply and advertising of medicines, pa ...
(TGA) of the Australian Government found that only one of their 23 approved
COVID-19 rapid antigen test COVID-19 rapid antigen tests or RATs, also frequently called COVID-19 lateral flow tests or LFTs, are rapid antigen tests used to detect SARS-CoV-2 infection (COVID-19). They are quick to implement with minimal training, cost a fraction of other ...
s (RAT) stated that it detected Omicron. In June 2022, the German federal Paul-Ehrlich-Institute published their findings, that most RATs detected the Omicron Variant.


Treatment

As of 28 November 2021,
Corticosteroid Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involv ...
s such as
dexamethasone Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena cav ...
and IL6 receptor blockers such as
tocilizumab Tocilizumab, sold under the brand name Actemra among others, is an immunosuppressive drug, used for the treatment of rheumatoid arthritis, systemic juvenile idiopathic arthritis, a severe form of arthritis in children, and COVID19. It is a hu ...
(Actemra) were known to be effective for managing patients with the earlier strains of severe COVID-19 but the impact on the effectiveness of other treatments was being assessed. Relating to
monoclonal antibodies A monoclonal antibody (mAb, more rarely called moAb) is an antibody produced from a cell Lineage made by cloning a unique white blood cell. All subsequent antibodies derived this way trace back to a unique parent cell. Monoclonal antibodies ca ...
(mAbs) treatments, similar testing and research is ongoing. Preclinical data on in vitro pseudotyped virus data demonstrate that some mAbs designed to use highly conserved epitopes retain neutralizing activity against key mutations of Omicron substitutions. Similar results are confirmed by cryo-electron microscopy and X-ray data, also providing the structural approach and molecular basis for the evasion of humoral immunity exhibited by Omicron antigenic shift as well as the importance of targeting conserved epitopes for vaccine and therapeutics design. While 7 clinical mAbs or mAb cocktails experienced loss of neutralizing activity of 1-2 orders of magnitude or greater relative to the prototypic virus, the S309 mAb, the parent mAb of
sotrovimab Sotrovimab, sold under the brand name Xevudy, is a human neutralizing monoclonal antibody with activity against severe acute respiratory syndrome coronavirus 2, known as SARS-CoV-2. Text was copied from this source which is copyright European M ...
, neutralized Omicron with only 2-3-fold reduced potency. As of December 2021, most monoclonal antibodies had lost in vitro neutralizing activity against Omicron, with only 3 out of 29 mAbs examined in another study retaining unaltered potency. Furthermore, a fraction of broadly neutralizing sarbecovirus mAbs neutralized Omicron through recognition of antigenic sites outside the RBM, including
sotrovimab Sotrovimab, sold under the brand name Xevudy, is a human neutralizing monoclonal antibody with activity against severe acute respiratory syndrome coronavirus 2, known as SARS-CoV-2. Text was copied from this source which is copyright European M ...
(VIR-7831), S2X259 and S2H97. However, sotrovimab was not fully active against the BA.2 Omicron sublineage, and in March2022 the office of the U.S. ASPR stopped distributing the antibody treatment to states where BA.2 was dominant. February 2022 data suggested Omicron caused significant humoral immune evasion, while neutralizing antibodies targeting the
sarbecovirus ''Severe acute respiratory syndrome–related coronavirus'' (SARSr-CoV or SARS-CoV)The terms ''SARSr-CoV'' and ''SARS-CoV'' are sometimes used interchangeably, especially prior to the discovery of SARS-CoV-2. This may cause confusion when some ...
conserved region remained most effective.


Epidemiology

On 26 November 2021, the South African
National Institute for Communicable Diseases The National Institute for Communicable Diseases (NICD) is the national public health institute of South Africa, providing reference to microbiology, virology, epidemiology, surveillance and public health research to support the government's re ...
announced that 30,904 COVID-19-tests (in one day) detected 2,828 new COVID-19 infections (a 9.2% positivity rate). One week later, on 3 December 2021, the NICD announced that 65,990 COVID-19 tests had found 16,055 new infections (5.7 times as many as seven days before; positive rate 24.3%) and that 72 percent of them were found in
Gauteng Gauteng ( ) is one of the nine provinces of South Africa. The name in Sotho-Tswana languages means 'place of gold'. Situated on the Highveld, Gauteng is the smallest province by land area in South Africa. Although Gauteng accounts for only ...
. This province of South Africa is densely populated at about 850 inhabitants per km2. Gauteng's capital
Johannesburg Johannesburg ( , , ; Zulu and xh, eGoli ), colloquially known as Jozi, Joburg, or "The City of Gold", is the largest city in South Africa, classified as a megacity, and is one of the 100 largest urban areas in the world. According to Demo ...
is a megacity (about 5.5 million inhabitants in the city itself plus 9.5 million in the urban region). In November 2021, the transmissibility of the Omicron variant, as compared to the Delta variant or other variants of the COVID-19 virus, was still uncertain. Omicron is frequently able to infect previously COVID-19-positive people. It has been estimated the Omicron variant diverged in late September or early October 2021, based on Omicron genome comparisons. Sequencing data suggests that Omicron had become the dominant variant in South Africa by November 2021, the same month where it had been first identified in the country. Phylogeny suggests a recent emergence. Data from South Africa suggests that Omicron has a pronounced growth advantage there. However, this may be due to transmissibility or immune escape related, or both." Also the serial interval plays a role in the growth. Detectable changes in levels of COVID-19 in wastewater samples from South Africa's Gauteng province were seen as early as 17–23 October (week 42). The National Institute for Communicable Diseases reports that children under the age of 2 make up 10% of total hospital admissions in the Omicron point of discovery
Tshwane The City of Tshwane Metropolitan Municipality (also known as the City of Tshwane) () is the metropolitan municipality that forms the local government of northern Gauteng Province, South Africa. The Metropolitan area is centred on the city of Pr ...
in South Africa. Data on the S gene target failure (SGTF) of sampled cases in South Africa indicates a growth of 21% per day relative to Delta, generating an increased reproduction number by a factor of 2.4. Omicron became the majority strain in South Africa around 10 November. Another analysis showed 32% growth per day in Gauteng, South Africa, having become dominant there around 6 November. In the UK, the logarithmic growth rate of Omicron-associated S gene target failure (SGTF) cases over S gene target positive (SGTP) cases was estimated at 0.37 per day, which is exceptionally high. Furthermore, by 14 December it appears to have become the most dominant strain. Without presuming behavior change in response to the variant, a million infections per day by 24 December are projected for a 2.5 days doubling time. In Denmark, the growth rate has been roughly similar with a doubling time of about 2–3 days, it having become the most prevalent strain on 17 December. Switzerland is not far behind. In Germany Omicron became the most prevalent variant on 1 January. In Scotland, Omicron apparently became the most prevalent variant on 17 December. In the Canadian province of Ontario it became the most prevalent strain on 13 December. In the US, the variant appears to have become the most prevalent strain on 18 December, growing at 0.24 per day. In Portugal, Omicron had reached 61.5% of cases on 22 December. In Belgium, the strain has become the most prevalent on 25 December, and in the Netherlands on 28 December. In Italy, it had reached 28% of cases on 20 December and was doubling every two days, while it became the dominant variant in Norway on 25 December. In France, it made up about 15% of COVID-19 cases in mid-December, but around 27 December it had increased to more than 60%. Researchers recommend sampling at least 5% of COVID-19 patient samples in order to detect Omicron or other emerging variants. During January 2022, in Denmark the BA.2 variant grew at ~0.10 per day (+11% per day) as a ratio to BA.1 (the legacy Omicron variant), and became the dominant strain in week 2, 2022. In the United Kingdom, the BA.2 variant was growing at ~0.11 per day (+12% per day) as a ratio to BA.1. On 13 January 2022, the
BBC #REDIRECT BBC #REDIRECT BBC Here i going to introduce about the best teacher of my life b BALAJI sir. He is the precious gift that I got befor 2yrs . How has helped and thought all the concept and made my success in the 10th board exam. ...
...
reported that the hospitalization rate was higher in the US and Canada than in Europe and South Africa. This was attributed to a combination of a greater number of elderly people than in South Africa, greater prevalence of comorbidities such as hypertension and obesity than in Europe, higher indoor transmission due to the winter, lower vaccination rate in the US than in Europe and Canada, and a possible still high prevalence of the
Delta variant The Delta variant (B.1.617.2) was a variant of SARS-CoV-2, the virus that causes COVID-19. It was first detected in India in late 2020. The Delta variant was named on 31 May 2021 and had spread to over 179 countries by 22 November 2021. The ...
, which more often leads to hospitalization.


Reported cases


See also

*
COVID-19 pandemic in Africa The COVID-19 pandemicpandemic was confirmed to have spread to Africa on 14 February 2020, with the first confirmed case announced in Egypt. The first confirmed case in sub-Saharan Africa was announced in Nigeria at the end of February 2020. W ...
**
COVID-19 vaccination in Africa COVID-19 vaccination programs have begun in many countries and territories in Africa. In June 2021, the World Health Organization predicted that 47 of Africa's 54 nations would fall short of the aim of vaccinating 10% of their people by Septemb ...
**
COVID-19 vaccination in Botswana COVID-19 vaccination in Botswana is an ongoing immunisation campaign against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), in response to the ongoing pandemic in the co ...
**
COVID-19 vaccination in South Africa COVID-19 vaccination in South Africa is an ongoing immunisation campaign against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19), in response to the ongoing pandemic in t ...
* Timeline of the SARS-CoV-2 Omicron variant, (November 2021-February 2022) *
Variants of SARS-CoV-2 There are many variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes coronavirus disease 2019 (COVID-19). Some are believed, or have been stated, to be of particular importance due to their potential ...
** Other variants of either interest or concern:
Alpha Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , whic ...
,
Beta Beta (, ; uppercase , lowercase , or cursive ; grc, βῆτα, bē̂ta or ell, βήτα, víta) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Modern Greek, it represents the voiced labiod ...
,
Gamma Gamma (uppercase , lowercase ; ''gámma'') is the third letter of the Greek alphabet. In the system of Greek numerals it has a value of 3. In Ancient Greek, the letter gamma represented a voiced velar stop . In Modern Greek, this letter re ...
,
Delta Delta commonly refers to: * Delta (letter) (Δ or δ), a letter of the Greek alphabet * River delta, at a river mouth * D ( NATO phonetic alphabet: "Delta") * Delta Air Lines, US * Delta variant of SARS-CoV-2 that causes COVID-19 Delta may also ...
,
Epsilon Epsilon (, ; uppercase , lowercase or lunate ; el, έψιλον) is the fifth letter of the Greek alphabet, corresponding phonetically to a mid front unrounded vowel or . In the system of Greek numerals it also has the value five. It was der ...
,
Zeta Zeta (, ; uppercase Ζ, lowercase ζ; grc, ζῆτα, el, ζήτα, label= Demotic Greek, classical or ''zē̂ta''; ''zíta'') is the sixth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 7. It was derived f ...
,
Eta Eta (uppercase , lowercase ; grc, ἦτα ''ē̂ta'' or ell, ήτα ''ita'' ) is the seventh letter of the Greek alphabet, representing the close front unrounded vowel . Originally denoting the voiceless glottal fricative in most dialects, ...
,
Theta Theta (, ; uppercase: Θ or ; lowercase: θ or ; grc, ''thē̂ta'' ; Modern: ''thī́ta'' ) is the eighth letter of the Greek alphabet, derived from the Phoenician letter Teth . In the system of Greek numerals, it has a value of 9. Gr ...
,
Iota Iota (; uppercase: Ι, lowercase: ι; ) is the ninth letter of the Greek alphabet. It was derived from the Phoenician letter Yodh. Letters that arose from this letter include the Latin alphabet, Latin I and J, the Cyrillic І (І, і), Yi (Cy ...
,
Kappa Kappa (uppercase Κ, lowercase κ or cursive ; el, κάππα, ''káppa'') is the 10th letter of the Greek alphabet, representing the voiceless velar plosive sound in Ancient and Modern Greek. In the system of Greek numerals, has a value o ...
,
Lambda Lambda (}, ''lám(b)da'') is the 11th letter of the Greek alphabet, representing the voiced alveolar lateral approximant . In the system of Greek numerals, lambda has a value of 30. Lambda is derived from the Phoenician Lamed . Lambda gave rise ...
, Mu *
Sikhulile Moyo Sikhulile Moyo is a Zimbabwean virologist working as the laboratory director of the Botswana–Harvard AIDS Institute Partnership and a research associate at the Harvard T.H. Chan School of Public Health. In November 2021, Moyo and his laborator ...
, scientist who discovered SARS-CoV-2 Omicron


Notes


References


Further reading

* WHO
Update on Omicron

Live Omicron Variant Location Map

Omicron variant: What have COVID vaccine makers said and are they working on new doses?
*


External links

* * Archived video: ** Archived at the an
Ghostarchive
** Archived at the an
Ghostarchive
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