Hepatitis B immunity in United States military recruits

Background. In 2002, the US Department of Defense (DoD) mandated hepatitis B immunization for military recruits. A DoD study reported that screening for immunity with selective immunization would be cost-effective at a prevalence of immunity of >12%. The prevalence of hepatitis B immunity in the military recruit population was unknown. Methods. We studied a random sample of Army, Navy, and Marine Corps new recruits (2400 men and women from all 50 states, Puerto Rico, and US territories). Banked serum samples collected in 2001 were tested for antibody to hepatitis B surface antigen (anti-HBs) by AUSAB enzyme-linked immunoassay (EIA). Results were evaluated by military service branch, age, sex, race, level of education, geographic region of origin, and presence of state immunization laws. Results. The overall prevalence of anti-HBs seropositivity, adjusted to the age distribution of the recruit population in 2001, was 31.5% (95% confidence interval [CI], 29.6%-33.4%). The prevalence of anti-HBs seropositivity, directly adjusted to the 18-35-year-old US population in 2000, was 23.0% (95% CI, 20.7%-25.3%). Anti-HBs seropositivity prevalence was highest among the young, decreased with increasing age, and was higher in women, recruits from the Northeast and West, and recruits from states with laws mandating hepatitis B immunization before entry into elementary and middle school. Conclusions. Screening new recruits for evidence of immunity before hepatitis B immunization is indicated. The prevalence of immunity increased with successive birth cohorts and may reflect the success of childhood immunization programs.