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Rising hepatitis A immunity in U.S. military recruits.

BACKGROUND
The U.S. military immunizes new recruits against hepatitis A. Since 2001, immunization with the hepatitis A vaccine has been recommended for civilian adolescents in higher risk areas. Recently, the Armed Forces Epidemiological Board recommended serologic screening where feasible to reduce redundant recruit immunizations.


OBJECTIVES
The purpose of this study was to determine hepatitis A seroprevalence in recruit populations to inform screening policy.


METHODS
Banked serum from a sample of military recruits (n = 2,592) in 2004 was tested for total antibody to hepatitis A (anti-hepatitis A virus (HAV)).


RESULTS
The overall anti-HAV seroprevalence was 12.0% (95% confidence interval, 10.8%-13.3%). Adjusted to the age distribution of the 18- to 34-year-old population, the seroprevalence was 11.9% (10.5%-13.4%). The lowest seroprevalence was noted in the 1984 birth cohort, with significantly higher seroprevalence among younger recruits.


CONCLUSIONS
Rising hepatitis A immunity among successive birth cohorts suggests increasing compliance with immunization recommendations. In anticipation of rising population immunity, universal screening of military recruits for anti-HAV is recommended.