response to the National Childhood Vaccine Injury Act of 1986.1 It is the nation’s principal system for the collection of reports on adverse events following the use of any vaccine licensed in the United States. The system is coadministered by two federal agencies, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA), which previously operated two separate surveillance systems. VAERS objectives include the following: (1) detecting previously unrecognized adverse events following the use of licensed vaccines; (2) detecting unusual increases in previously reported events; (3) detecting preexisting conditions that may promote adverse events and contraindicate additional vaccine doses; (4) detecting vaccine lots for which unusual numbers and unusual types of events are reported; (5) serving as a registry for rare vaccine-related adverse events; and (6) providing national data on the numbers of reported adverse events by vaccine type and recipient age (Singleton et al., 1999). It is also intended to trigger further clinical, epidemiologic, or laboratory studies of vaccine safety (Chen, 2000; Mootrey, 2000).
VAERS receives spontaneous reports of adverse events following vaccination. From 1990, when VAERS began, through December 2001, VAERS received more than 126,000 reports on events associated with vaccines of all types (Iskander, 2002). Anyone can submit a report to VAERS, including vaccine recipients or their family members, and more than one report can be submitted about the same adverse event. Reporting is encouraged for any clinically significant event following vaccination, but health care providers are required to report any event listed by the manufacturer as a contraindication to the administration of additional doses of the vaccine as well as certain other specified events (VAERS, 2001). Most reports are submitted by health care providers directly (30 percent) or through the vaccine manufacturer (42 percent; Iskander, 2001b). Figure 5-1 illustrates the flow of information into and through VAERS.
Each year, reporting forms along with instructions and a cover letter encouraging reporting are mailed to about 200,000 health care providers (Iskander, 2001a). The forms are also available on the Internet (http://www.vaers.org/, http://www.fda.gov/cber/vaers/vaers.htm, http://www.cdc.gov/nip/). A VAERS report form includes spaces for the reporter to provide demographic information about the vaccine recipient and an open-ended description of the adverse event(s), treatment, outcome, relevant laboratory or diagnostic information, timing of the vaccination and the adverse event,