Adverse Events Reporting (VAERS)

Once a vaccine is licensed for use, it is still watched carefully for problems, called adverse events. Anyone who gives or receives a licensed vaccine in the United States should report any adverse events (even if unsure that the vaccine caused the problem) for any vaccine. The Vaccine Adverse Event Reporting System (VAERS) is a vaccine safety program sponsored by the Centers for Disease Control and Prevention (CDC) and the U.S. Food and Drug Administration (FDA).

Patients can use VAERS to report any problems they have had with vaccines. VAERS also provides information on vaccine safety. VAERS data are monitored to:

  • Detect new, unusual, or rare vaccine adverse events
  • Monitor increases in known adverse events
  • Identify potential patient risk factors for particular types of adverse events
  • Identify vaccine lots with increased numbers or types of reported adverse events
  • Assess the safety of newly licensed vaccines

Approximately 30,000 VAERS reports are filed annually, with 10-15% classified as serious (resulting in permanent disability, hospitalization, life-threatening illnesses or death). Anyone can file a VAERS report, including health care providers, manufacturers, and vaccine recipients or their parents or guardians.

The VAERS form requests the following information:

  • The type of vaccine received
  • The timing of the vaccination
  • The onset of the adverse event
  • Current illnesses or medication
  • Past history of adverse events following vaccination
  • Demographic information about the recipient

VAERS forms can be completed online, or you can complete a paper form and mail or fax it to VAERS.

A contractor, under the supervision of FDA and CDC, enters the information from VAERS forms into a database. Those reporting an adverse event to VAERS receive a confirmation letter containing a VAERS identification number.

Additional information may be submitted to VAERS using the assigned identification number. Selected cases of serious adverse reactions are followed up at 60 days and one year post-vaccination to check the recovery status of the patient. FDA and CDC use VAERS data to monitor vaccine safety and conduct research studies. VAERS data (without identifying personal information) are also available to the public.

While VAERS provides useful information on vaccine safety, the data are somewhat limited. For example, VAERS reports may provide incomplete information. Specifically, judgments about whether the vaccine was truly responsible for an adverse event cannot be made from VAERS reports.


This website is supported by an independent educational grant from Merck and an educational grant from Sanofi Pasteur U.S. 
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