Visit for the latest Coronavirus Disease (COVID-19) updates.

You are here

In This Section:

Vaccine Adverse Event Reporting System


VAERS is a national post-marketing vaccine safety surveillance program cosponsored. VAERS collects information about adverse events (possible side effects) that occur after the administration of vaccines licensed in the U.S. It provides a nationwide mechanism by which adverse events following immunization may be reported, analyzed, and made available to the public. It also provides a vehicle for disseminating vaccine safety related information to parents and guardians, healthcare providers, vaccine manufacturers, state vaccination programs, and other constituencies.

Centers for Disease Control and Prevention and Food and Drug Administration
Data Years Available: 
Mode of Collection: 
Voluntary submission of reports.
Selected Content: 
Information can be accessed on symptoms, vaccine products, adverse event characteristics, manufacturers, patient characteristics, vaccination date, report date, and patient outcome.
Population Covered: 

VAERS seeks reports of any clinically significant medical event that occurs after vaccination, even if the reporter cannot be certain that the event was caused by the vaccine. CDC/Immunization Safety Office (ISO) and the Food and Drug Administration (FDA) review adverse reports; VAERS has identified important signals that after further research resulted in changes to vaccine recommendations. The majority of VAERS reports are sent in by vaccine manufacturers (37%) and health care providers (36%). The remaining reports are obtained from state immunization programs (10%), vaccine recipients (or their parent/guardians, 7%) and other sources (10%).

Response Rates and Sample Size: 
Interpretation Issues: 

When evaluating data from VAERS, it is important to note that for any reported event, no cause-and-effect relationship has been established.