​Vaccine Adverse Even​ts Reporting System​

Even after an extensive and exhaustive process of verifying that an immunization is effective and safe, the safety of that immunization is scrutinized and tracked for years through the Vaccine Adverse Event Reporting System (VAERS). Promoted by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA), "VAERS is a post-marketing safety surveillance program, collecting information about adverse events (possible side effects) that occur after the administration of vaccines licensed for use in the United States."

  • Immunizations are tracked for adverse events after licensing through VAERS.
  • Anyone with a concern about an adverse immunization event can report to VAERS.
  • VAERS does not define causality between the immunization and adverse event.
  • Patterns in reports to VAERS can be studied and investigated through the Vaccine Safety Datalink.

The primary objectives of VAERS are 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.

Any medical event that occurs after a vaccine administration should be reported, even if the reporter cannot be sure that the vaccine caused the event. The National Childhood Vaccine Injury Act requires healthcare providers to report the following​:

The job of VAERS is to assist the medical community in evaluating causation; therefore, the more reports given to the system, the more effective the results.

Report to VAERS​.


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