Vaccine-associated enhanced respiratory disease (VAERD), or simply enhanced respiratory disease (ERD), refers to an adverse event where an exacerbated course of respiratory disease occurs with higher incidence in the vaccinated population in comparison with the

control group In the design of experiments, hypotheses are applied to experimental units in a treatment group. In comparative experiments, members of a control group receive a standard treatment, a placebo, or no treatment at all. There may be more than one tr ...

. It is one of the barriers against vaccine development and can lead to its failure. Immunologically, VAERD is characterized with an exaggerated Th2 response and

eosinophilic Eosinophilic (Greek suffix -phil-, meaning ''loves eosin'') is the staining of tissues, cells, or organelles after they have been washed with eosin, a dye. Eosin is an acidic dye for staining cell cytoplasm, collagen, and muscle fibers. ''Eosi ...

pulmonary infiltrations. It is thought to arise as a result of antibody-mediated complement activation followed by weak neutralization. Historical instances of the phenomenon were seen in vaccine candidates for

respiratory syncytial virus Respiratory syncytial virus (RSV), also called human respiratory syncytial virus (hRSV) and human orthopneumovirus, is a common, contagious virus that causes infections of the respiratory tract. It is a negative-sense, single-stranded RNA virus. ...

SARS-CoV Severe acute respiratory syndrome coronavirus 1 (SARS-CoV-1; or Severe acute respiratory syndrome coronavirus, SARS-CoV) is a strain of coronavirus that causes severe acute respiratory syndrome (SARS), the respiratory illness responsible for t ...

Middle East Respiratory Syndrome Middle East respiratory syndrome (MERS) is a viral respiratory infection caused by ''Middle East respiratory syndrome–related coronavirus'' (MERS-CoV). Symptoms may range from none, to mild, to severe. Typical symptoms include fever, cough, ...

(MERS), as well as some

Influenza Influenza, commonly known as "the flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms ...

strains. During the efforts to develop

COVID-19 vaccines 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 est ...

, whose target,

SARS-CoV2 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 p ...

, belongs to the same viral subfamily as SARS-CoV and MERS, concerns were raised about the possibility of exhibiting VAERD. Despite being monitored, the effect wasn't shown in

phase III clinical trials The phases of clinical research are the stages in which scientists conduct experiments with a health intervention to obtain sufficient evidence for a process considered effective as a medical treatment. For drug development, the clinical phases ...

for both Tozinameran and the

Moderna vaccine The Moderna COVID19 vaccine (INN: elasomeran), sold under the brand name Spikevax, is a COVID-19 vaccine developed by American company Moderna, the United States National Institute of Allergy and Infectious Diseases (NIAID), and the Biomedi ...

.{{cite report, url=https://www.fda.gov/media/144337/download, title=FDA Review of Efficacy and Safety of Pfizer-BioNTech COVID-19 Vaccine Emergency Use Authorization Request, date=10 December 2020, access-date=11 December 2020, format=PDF, website=U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...

(FDA)

References

Vaccination Drug-induced diseases