Postmarketing Safety Surveillance for Typhoid Fever Vaccines from the Vaccine Adverse Event Reporting System, July 1990 through June 2002

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Abstract
Vaccines against Salmonella enterica serotype Typhi are used for prophylaxis of international travelers and have potential use as counterbioterrorism agents. The Vaccine Adverse Event Reporting System (VAERS) cannot usually establish causal relationships between vaccines and reported adverse events without further research but has successfully detected unrecognized side effects of vaccine. We reviewed reports to VAERS for US-licensed typhoid fever vaccines for the period of July 1990 through June 2002. We received 321 reports for parenteral Vi capsular polysaccharide vaccine and 345 reports for live, oral, attenuated Ty21a vaccine, with 7.5% and 5.5%, respectively, describing death, hospitalization, permanent disability, or life-threatening illness. Unexpected frequently reported symptoms included dizziness and pruritus for Vi vaccine and fatigue and myalgia for Ty21a vaccine. Gastroenteritis-like illness after receipt of Ty21a vaccine and abdominal pain after receipt of Vi vaccine, which are previously recognized events, occasionally required hospitalization. Nonfatal anaphylaxis was reported after both vaccines. VAERS reports do not indicate any unexpected serious side effects that compromise these vaccines' use for travelers' prophylaxis.