Immune Response to Hepatitis A Vaccine Combined or Given Simultaneously with Typhoid Fever Vaccine

Background: Because both hepatitis A and typhoid vaccination are frequently indicated in the same traveler, a prospective, randomized controlled study was performed to evaluate the feasibility of simultaneous administration of hepatitis A and typhoid fever vaccines in adult volunteers. Methods: Two groups of 25 subjects received either separate injections of hepatitis A (Havrixtrade mark, SmithKline Beecham Biologicals) and typhoid fever (Typhim Vitrade mark, Pasteur-Mérieux) vaccines in opposite arms, or a syringe-mixed combination of both vaccines as a single injection. A booster dose of Havrix was given at 6 months. Results: The immune response to hepatitis A tended to be higher in the mixed-injection group, but this difference was significant (p=.048) only following the booster dose. Adverse reactions were generally mild with no differences between the two groups. Conclusion: A combined formulated vaccine against both typhoid fever and hepatitis A is feasible and offers more convenience without added adverse reactions to travelers who have appropriate indications for both vaccines.