Reports of flu-like symptoms after COVID-19 vaccination

At a virtual meeting held on 25 February 2021, WHO's Global Advisory Committee on Vaccine Safety (GACVS) COVID-19 Subcommittee reviewed reports of flu-like symptoms after COVID-19 vaccination, and concluded that the symptoms are expected and do not change the benefit-risk balance of COVID-19 vaccines.

At the time of this review, the WHO global Individual Case Safety Reports database, Vigibase, had received reports of flu-like symptoms after vaccination with AZD-122 [ChAdOx1-nCoV-19 vaccine; AstraZeneca], tozinameran [Pfizer-BioNTec COVID-19 vaccine], mRNA-1273 [Moderna COVID-19 vaccine], and SARS-COV-2 vaccine inactivated (Vero cell; CZ02) [Sinovac].

Symptoms of flu-like illness, including fatigue, muscle aches, fever and chills, were reported in several countries and had also been reported after COVID-19 vaccination in clinical trials. Most symptoms were mild to moderate and transient. These adverse effects were more frequently reported in vaccine recipients under 55 years of age.

The COVID-19 Subcommittee concluded that flu-like symptoms may be expected as immune responses following vaccinations in general, and current reports after COVID-19 vaccination are consistent with the expected side-effect profile of these vaccines, all of which were well tolerated. It recommends that people should be informed of the potential for flu-like symptoms prior to COVID-19 vaccination, and says that transient symptoms such as headache, fever and muscle aches after a first dose of these vaccines should not prevent administration of the second dose.

The committee recommends that reports of suspected adverse events should be collected and reviewed continuously as COVID-19 vaccines are rolled out world-wide, in order to ensure their continuing positive benefit-risk balance.