![SIR model anim](https://upload.wikimedia.org/wikipedia/commons/2/20/SIR_model_anim.gif)
Flattening the curve was a
public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...
strategy to slow down the spread of the
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 ...
virus during the early stages of the
COVID-19 pandemic
The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identif ...
. The curve being flattened is the
epidemic curve
An epidemic curve, also known as an epi curve or epidemiological curve, is a statistical chart used in epidemiology to visualise the onset of a disease outbreak. It can help with the identification of the mode of transmission of the disease. It ca ...
, a visual representation of the number of infected people needing health care over time. During an epidemic, a health care system can break down when the number of people infected exceeds the capability of the health care system's ability to take care of them. Flattening the curve means slowing the spread of the epidemic so that the peak number of people requiring care at a time is reduced, and the health care system does not exceed its capacity. Flattening the curve relies on mitigation techniques such as
hand washing
Hand washing (or handwashing), also known as hand hygiene, is the act of cleaning one's hands with soap, soap or handwash and water to remove viruses/bacteria/microorganisms, dirt, grease, or other harmful and unwanted substances stuck to the ...
, use of face masks and
social distancing
In public health, social distancing, also called physical distancing, (NB. Regula Venske is president of the PEN Centre Germany.) is a set of non-pharmaceutical interventions or measures intended to prevent the spread of a contagious disea ...
.
A complementary measure is to increase health care capacity, to "raise the line".
As described in an article in ''
The Nation
''The Nation'' is an American liberal biweekly magazine that covers political and cultural news, opinion, and analysis. It was founded on July 6, 1865, as a successor to William Lloyd Garrison's '' The Liberator'', an abolitionist newspaper tha ...
'', "preventing a health care system from being overwhelmed requires a society to do two things: 'flatten the curve'—that is, slow the rate of infection so there aren't too many cases that need hospitalization at one time—and 'raise the line'—that is, boost the hospital system's capacity to treat large numbers of patients."
During 2020, in the early stages of the
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 ...
pandemic, two key measures were to increase the numbers of available
ICU beds and
ventilator
A ventilator is a piece of medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insufficiently. Ventilators ...
s, which were in
systemic shortage.
Experts differentiate between "
zero-COVID
Zero-COVID, also known as COVID-Zero and "Find, Test, Trace, Isolate, and Support" (FTTIS), is a public health policy that has been implemented by some countries during the COVID-19 pandemic.Anna Llupià, Rodríguez-Giralt, Anna Fité, Lola Ála ...
", which is an elimination strategy taken by China, and "flattening the curve", a
mitigation
Mitigation is the reduction of something harmful or the reduction of its harmful effects. It may refer to measures taken to reduce the harmful effects of hazards that remain ''in potentia'', or to manage harmful incidents that have already occur ...
strategy that attempts to lessen the effects of the virus on society as much as possible, but still tolerates low levels of transmission within the community.
These two initial strategies can be pursued sequentially or simultaneously during the
acquired immunity phase through
natura
Natura & Co is a Brazilian global personal care cosmetics group headquartered in São Paulo. The Natura & Co Group currently includes Natura Cosméticos, Aesop, The Body Shop and Avon Products. The Group is present in 73 countries across all cont ...
l and
vaccine-induced immunity.
Background
Warnings about the risk of pandemics were repeatedly made throughout the 2000s and the 2010s by major international organisations including 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) and the
World Bank
The World Bank is an international financial institution that provides loans and grants to the governments of low- and middle-income countries for the purpose of pursuing capital projects. The World Bank is the collective name for the Interna ...
, especially after the
2002–2004 SARS outbreak
The 2002–2004 outbreak of SARS, caused by severe acute respiratory syndrome coronavirus (SARS-CoV or SARS-CoV-1), infected over 8,000 people from 29 countries and territories, and resulted in at least 774 deaths worldwide.
The outbreak wa ...
.
Governments, including those in 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 ...
and
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 ...
, both prior to the
2009 swine flu pandemic
The 2009 swine flu pandemic, caused by the H1N1 influenza virus and declared by the World Health Organization (WHO) from June 2009 to August 2010, is the third recent flu pandemic involving the H1N1 virus (the first being the 1918–1920 Span ...
, and during the decade following the pandemic, both strengthened their health care capacities and then weakened them.
At the time of the COVID-19 pandemic, health care systems in many countries were functioning near their maximum capacities.
In a situation like this, when a sizable new epidemic emerges, a portion of infected and symptomatic patients create an increase in the demand for health care that has only been predicted statistically, without the start date of the epidemic nor the infectivity and lethality known in advance.
If the demand surpasses the capacity line in the infections per day curve, then the existing health facilities cannot fully handle the patients, resulting in higher death rates than if preparations had been made.
An influential UK study showed that an unmitigated COVID-19 response in the UK could have required up to 46 times the number of available
ICU beds.
One major
public health management challenge is to keep the epidemic wave of incoming patients needing material and human health care resources supplied in a sufficient amount that is considered medically justified.
Flattening the curve
Queue markers at a shopping mall in Bangkok as a
social distancing
In public health, social distancing, also called physical distancing, (NB. Regula Venske is president of the PEN Centre Germany.) is a set of non-pharmaceutical interventions or measures intended to prevent the spread of a contagious disea ...
practicing
Non-pharmaceutical intervention (epidemiology), Non-pharmaceutical interventions such as
hand washing
Hand washing (or handwashing), also known as hand hygiene, is the act of cleaning one's hands with soap, soap or handwash and water to remove viruses/bacteria/microorganisms, dirt, grease, or other harmful and unwanted substances stuck to the ...
,
social distancing
In public health, social distancing, also called physical distancing, (NB. Regula Venske is president of the PEN Centre Germany.) is a set of non-pharmaceutical interventions or measures intended to prevent the spread of a contagious disea ...
,
isolation and
disinfection
A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than st ...
reduce the daily infections, therefore flattening the epidemic curve. A successfully flattened curve spreads health care needs over time and the peak of hospitalizations under the health care capacity line.
Doing so, resources, be it material or human, are not exhausted and lacking. In hospitals, it for medical staff to use the proper protective equipment and procedures, but also to separate contaminated patients and exposed workers from other populations to avoid patient-to-doctor or patient-to-patient spreading.
Raising the line
Along with the efforts to flatten the curve is the need for a parallel effort to "raise the line", to increase the capacity of the health care system.
Healthcare capacity can be raised by raising equipment, staff, providing
telemedicine, home care and health education to the public.
Elective procedures can be cancelled to free equipment and staffs.
Raising the line aims to provide adequate medical equipment and supplies for more patients.
During the COVID-19 pandemic
![Katapult importance social distancing](https://upload.wikimedia.org/wikipedia/commons/8/82/Katapult_importance_social_distancing.gif)
The concept was popular during the early months of the COVID-19 pandemic.
According to
Vox, in order to move away from social distancing and return to normal, the US needs to flatten the curve by isolation and mass testing, and to raise the line.
Vox encourages building up health care capability including mass testing, software and infrastructures to trace and quarantine infected people, and scaling up cares including by resolving
shortages
In economics, a shortage or excess demand is a situation in which the demand for a product or service exceeds its supply in a market. It is the opposite of an excess supply (surplus).
Definitions
In a perfect market (one that matches ...
in
personal protection equipment,
face masks.
According to ''The Nation'', territories with weak finances and health care capacity such as
Puerto Rico
Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...
face
an uphill battle to raise the line, and therefore a higher imperative pressure to flatten the curve.
In March 2020,
UC Berkeley
The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public university, public land-grant university, land-grant research university in Berkeley, California. Established in 1868 as the University of Californi ...
Economics and Law professor
Aaron Edlin
Aaron S. Edlin (born 1967) is an American economist and lawyer specializing in antitrust and competition policy. In 1997–1998, he served in the Clinton White House as Senior Economist within the Council of Economic Advisers focusing on the ar ...
commented that ongoing massive efforts to flatten the curve supported by trillions dollars emergency package should be matched by equal efforts to raise the line and increase health care capacity.
Edlin called for an activation of the
Defense Production Act
The Defense Production Act of 1950 () is a United States federal law enacted on September 8, 1950 in response to the start of the Korean War.Congressional Research ServiceThe Defense Production Act of 1950: History, Authorities, and Considerati ...
to order manufacturing companies to produce the needed
sanitizers,
personal protective equipment
Personal protective equipment (PPE) is protective clothing, helmets, goggles, or other garments or equipment designed to protect the wearer's body from injury or infection. The hazards addressed by protective equipment include physical, elec ...
,
ventilators
A ventilator is a piece of medical technology that provides mechanical ventilation by moving breathable air into and out of the lungs, to deliver breaths to a patient who is physically unable to breathe, or breathing insufficiently. Ventilators ...
, and set up hundreds thousands to millions required
hospital beds.
Standing in March 2020 estimates, Edlin called for the construction of 100-300 emergency hospitals to face what he described as "the largest health catastrophe in 100 years" and to adapt health care legislation preventing emergency practices needed in time of pandemics.
Edlin pointed out proposed stimulus package as oriented toward financial panics, while not providing sufficient funding for the core issue of a pandemic: health care capability.
By 2021, the phrase "flatten the curve" had largely fallen out of medical messaging etymology.
See also
*
SIR model
Compartmental models are a very general modelling technique. They are often applied to the mathematical modelling of infectious diseases. The population is assigned to compartments with labels – for example, S, I, or R, (Susceptible, Infectious, ...
*
Basic reproduction number
In epidemiology, the basic reproduction number, or basic reproductive number (sometimes called basic reproduction ratio or basic reproductive rate), denoted R_0 (pronounced ''R nought'' or ''R zero''), of an infection is the expected number of ...
(''R''
0)
*
Quarantine
A quarantine is a restriction on the movement of people, animals and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have been ...
*
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 ...
*
List of countries by hospital beds
The number of beds per people is an important indicator of the health care system of a country. The basic measure focus on all hospital beds, which are variously split and occupied. The classic hospital beds are also called curative beds. For seve ...
References
{{COVID-19 pandemic
Epidemiology
Responses to the COVID-19 pandemic