What you need to know
- VAERS is a public database where anyone can report a health issue after vaccination. The reports are unverified when submitted.
- Scientists use VAERS as an early warning system to detect unusual patterns and investigate possible side effects. But VAERS reports alone can’t be used to determine if a vaccine caused a health issue.
- Especially since the COVID-19 pandemic, VAERS data has been misused to spread false claims about vaccine safety.
To make sure vaccines are safe, the U.S. uses several vaccine monitoring systems to detect rare side effects that may not appear in clinical trials. Increasingly, since the COVID-19 pandemic anti-vaccine activists have often misleadingly used data from VAERS. This has led to widespread confusion about what VAERS is and false claims about vaccine safety.
Anyone can submit a report to VAERS, and the information is unverified when first entered. Scientists then review patterns and follow up with other data sources to confirm whether a vaccine could be linked to a reported health problem. Below, learn more how VAERS works, how its data should be interpreted, and how the broader vaccine safety system protects the public.
What is VAERS?
In 1990, the Centers for Disease Control and Prevention and the Food and Drug Administration created VAERS to help detect potential safety concerns after vaccination in the United States. The database is public and searchable, and anyone can report a health issue (known as an adverse event) that happens after getting vaccinated.
VAERS is one of several national programs that monitor vaccine safety. While it can help identify very rare side effects, VAERS reports alone cannot show whether a vaccine caused a health problem.
Because anyone can submit a report, the information submitted may be “incomplete, inaccurate, coincidental, or unverifiable,” says the CDC. Scientists use the reports to look for patterns, then follow up with further investigation before drawing conclusions.
How does VAERS work?
Any person can submit a report through the VAERS website. The process is simple by design so that even small or unusual health issues are captured for review. Because anyone can submit a report, the system includes many unverified entries, some of which are not related to vaccination. For example, someone may report a side effect that could have been caused by another condition or coincidence.
“The agencies closely monitor these reports and investigate health concerns that occur more often than expected,” PGN reported in March. “When a potential safety concern is detected, health officials promptly alert health care providers and the public.”
Over the years, VAERS has helped identify rare side effects from vaccines. For COVID-19 vaccines, one example was anaphylaxis, a severe allergic reaction. This reaction is extremely rare, occurring in about five cases per 1 million doses administered.
How should the VAERS database be interpreted?
Particularly since the COVID-19 pandemic, VAERS data has been misused to spread false claims that vaccines are unsafe. In reality, as FactCheck.org explains, VAERS is designed to flag possible concerns for scientists to investigate further, not to confirm that a vaccine caused a reported side effect.
“VAERS is a system that generates hypotheses,” explained Dr. Demetre Daskalakis, former director of the CDC’s National Center for Immunization and Respiratory Diseases, in a post on X. “It is designed to be a very low threshold system for everyone, patients and providers, to submit adverse events for additional review and to generate more study.”
VAERS is just one part of a broader safety network. Other programs include V-safe, the Vaccine Safety Datalink, and the Clinical Immunization Safety Assessment Project. Together, these systems monitor vaccine safety and ensure the public is informed if a real risk is identified.
For more information, talk to your health care provider.