vaccine type and lot number, and preexisting conditions. (See Appendix E for a copy of the form.)
Reports can be submitted by mail or fax, or the information can be provided over the telephone. Reports are submitted to the VAERS contractor, who acknowledges their receipt with a letter to the reporter (Chen et al., 1994; Singleton et al., 1999). The contractor assigns a unique identifier to each report, assigns codes to the adverse events reported, and enters the data into a computer database. Duplicate reports are removed or linked if the different reports provide different information (Iskander, 2001a).
Certain adverse events are classified as serious2: a death, a life-threatening illness, or an illness that results in a permanent disability, hospitalization, or prolongation of a hospital stay (Singleton et al., 1999). Manufacturers are also required to report “other medically important conditions” (Iskander, 2001b). Within 5 days of the receipt of a report of a serious event, nurses working for the VAERS contractor initiate follow-up inquiries to the vaccine recipient or reporter to gather more information, including medical or autopsy records, if they are available (E. Miller, CDC,