The Vaccine Adverse Event Reporting System (VAERS) is a passive monitoring system that collects reports of adverse events that occur following administration of a vaccine. Importantly, adverse events reported to VAERS are not confirmed as side effects caused by vaccines, and the system cannot be used to calculate the risk of any particular adverse event, whether confirmed to result from a vaccine or not.
Any individual — including patients and physicians — can report an event to VAERS, and reported incidents include biologically plausible side effects, such as fevers, as well as incidents that could not have been caused by vaccines, such as car accidents. VAERS serves as an early warning system that prompts researchers to conduct formal studies on adverse events that occur more frequently than others and are biologically plausible side effects of vaccines. VAERS was established in 1990 as a result of the National Childhood Vaccine Injury Act of 1986 (NCVIA).
For additional information on VAERS and its limitations, see the following links:
- What VAERS Is (And Isn’t) from Johns Hopkins.
- Safety monitoring in the Vaccine Adverse Event Reporting System (VAERS) from the journal Vaccine.
- VAERS Frequently Asked Questions (FAQs) at HHS (archived).
- Guide to Interpreting VAERS Data at HHS (archived).
- VAERS: A Critical Part of the National Vaccine Safety System at CDC.
- About the Vaccine Adverse Event Reporting System (VAERS) at CDC.