Vaccine Adverse Event Reporting System

The Vaccine Adverse Event Reporting System (VAERS) is a United States program for vaccine safety, co-managed by the U.S. Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA). VAERS is a postmarketing surveillance program, collecting information about adverse events (possible side effects) that occur after administration of vaccines.

VAERS, the Vaccine Safety Datalink, and the Clinical Immunization Safety Assessment (CISA) Network are tools by which the CDC and FDA measure vaccine safety to fulfill their duty as regulatory agencies charged with protecting the public. Some scientists would like to do a more scientifically rigorous job of this, noting that VAERS has several limitations, including reports, underreporting, inconsistent data quality, and absence of an unvaccinated control group.

The program is an outgrowth of the 1986 National Childhood Vaccine Injury Act (NCVIA), which requires health care providers to report:

VAERS was established in 1990, and is managed jointly by the FDA and the CDC. It is meant to act as a sort of "early warning system"—a way for physicians and researchers to identify possible unforeseen reactions or side effects of vaccination for further study.

Each year the VAERS receives 10,000–20,000 reports of adverse events following immunization by more than 10 million vaccines. Higher-priority uses of the data include reports of death and other serious adverse events, recognizing and detecting adverse effects, and finding unexpected adverse events involving new vaccines. The VAERS data are also used to monitor known reactions to vaccines and for vaccine lot surveillance. Data mining techniques such as empirical Bayes methods can be used to improve the quality of data analysis.

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