Vaccine Adverse Event Reporting System

The Vaccine Adverse Event Reporting System is a United States program for vaccine safety, co-sponsored 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 administration of vaccines.

Origins
The program is an outgrowth of the 1986 National Childhood Vaccine Injury Act (NCVIA), which requires health care providers to report:
 * Any event listed by the vaccine manufacturer as a contraindication to subsequent doses of the vaccine.
 * Any event listed in the Reportable Events Table that occurs within the specified time period after vaccination. The data are stored electronically by the CDC in the Vaccine Safety Datalink (VSD).

The FDA claims that "Very rarely, people experience serious adverse events following immunization." The FDA says 15 percent of the 123,000 adverse events reported since 1990 "reflect serious adverse events involving life-threatening conditions, hospitalization, permanent disability, or death, which may or may not have been truly caused by an immunization."

VAERS is meant to act as a sort of "early warning system"&mdash;a way for physicians and researchers to identify possible unforeseen reactions or side effects of vaccination for further study.

Research use
Many medical researchers make use of VAERS to study the effects of vaccination. VAERS instructs researchers using its database::


 * Establishing causal relationships between vaccines and adverse events requires additional scientific investigation.
 * The CDC and FDA take into account the complex factors mentioned above, and others, when monitoring vaccine safety and analyzing VAERS reports.
 * The purpose of VAERS is to detect possible signals of adverse events associated with vaccines. Additional scientific investigations are almost always required to properly validate signals from VAERS and establish a cause and effect relationship between a vaccine and an adverse event.

Litigation as a source of bias
A 2006 study in Pediatrics showed that there was a clear increase in VAERS reports related to litigation. In 2002, nearly one third of the reports were related to litigation. The authors suggest that litigation-related reports may skew trends.