The Vaccine Adverse Event Reporting System, a U.S. government database established in 1990 to collect reports of health events following vaccination, jointly operated by the CDC and FDA.
VAERS is a passive surveillance system created in 1990 by the Centers for Disease Control and Prevention (CDC) and Food and Drug Administration (FDA) to monitor vaccine safety in the United States. The system accepts reports from healthcare providers, manufacturers, and the public about adverse events temporally associated with vaccination. VAERS data is publicly accessible through online databases and is used by health agencies to identify potential safety signals requiring further investigation. Importantly, VAERS reports do not prove causation; they document temporal correlation and are designed to generate hypotheses for rigorous follow-up studies.
VAERS became widely discussed during the COVID-19 pandemic, with over 13,000 deaths reported to VAERS following COVID-19 vaccination between December 2020 and September 2021. However, CDC analysis of autopsy reports and medical records found no causal link in reviewed cases, and epidemiological studies comparing vaccinated to unvaccinated populations showed vaccines were associated with reduced mortality overall. The system's strength is sensitivity (capturing potential signals); its weakness is specificity (distinguishing vaccine effects from coincidental health events). Researchers, regulators, and the public cite VAERS data, but health agencies emphasize that reports require investigation before conclusions about causation can be drawn. This distinction has become central to debates about vaccine safety communication.
