The World Health Organization (WHO) reports that the GACVS COVID-19 Subcommittee met virtually on Thursday, 25 February 2021, to review available information and data on reports of influenza-like illness in health-care workers who had received COVID-19 vaccines. These symptoms have been reported in several countries. The Subcommittee reviewed clinical trial data and a summary of reports of influenza-like illness following vaccination with COVID-19 vaccines in the WHO global Individual Case Safety Reports database (VigiBase).
The Subcommittee noted that similar symptoms of influenza-like illness had also been reported in the first few days following vaccination with COVID-19 vaccines in clinical trials. These included headache, fatigue, muscle aches, feverishness and chills. Most symptoms were mild to moderate and resolved within a few days. These expected side effects from vaccination were more common in younger vaccine recipients (under the age of 55 years) compared with older people.
Based on a careful scientific review of the information made available, the Subcommittee came to the following conclusions:
- Symptoms of an influenza-like illness may be expected as immune responses following vaccinations in general.
- The current reports with the COVID-19 vaccines are consistent with the expected side-effect profile of these vaccines, all of which were well tolerated.
Benefit-Risk Analyses Favors Vaccine
In view of this, the committee considers that the benefit-risk balance of the COVID-19 vaccines (for which reports of the influenza-like reactions are available to date) remains favorable and does not suggest any revision, at present, to the recommendations around the safety of these vaccines.
Inform & Empowered Patients
The committee recommends that people who are vaccinated be informed, prior to vaccination, of the potential for influenza-like symptoms to occur after receipt of COVID-19 vaccines. Such symptoms should be managed accordingly, with medical advice sought if required. The occurrence of 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 potential for short-term adverse events following vaccination should be considered when planning the timing of vaccination for healthcare teams or other workers covering a specific service area.
All countries should continue to monitor the safety of vaccines and promote routine after-care following immunization, consistent with good immunization practices for any vaccine. The committee recommends that data on suspected adverse events should be collected and reviewed continuously — nationally, regionally, and globally — as the COVID-19 vaccines are rolled out, world-wide, in order to ensure their continuing positive benefit risk balance.
The GACVS subcommittee will continue to review the safety data from all COVID-19 vaccines and update any advice as necessary.
The WHO COVID-19 vaccine safety surveillance manual provides guidance to countries on the safety monitoring and adverse events data sharing for the new COVID-19 vaccines, and can be accessed here.
 At the time of this review, the WHO global Individual Case Safety Reports database, Vigibase, included reports of influenza-like illness following vaccinations with NRVV Ad (ChAdOx1 nCoV-19) (AZ), Tozinameran (Pfizer), mRNA 1273 (Moderna), COVID-19 vaccine inact (Vero) CZ02 (Sinovac) vaccines. WHO will continue to monitor for potential reports of similar events following other COVID-19 vaccines.