Benefits of Serologic Screening for Hepatitis B Immunity in Military Recruits

To the Editor—Scott et al. present rates of hepatitis B immunity among US military recruits and predict increasing immunity over time on the basis of their finding of increasing immunity in successive birth cohorts [1]. We present confirmation of this prediction, from recent serosurveillance efforts, which suggested widespread acceptance of childhood [2] and adolescent [3] immunization recommendations among the birth cohorts entering military service. On the basis of the recent internal release of the results of Scott et al. [1], which revealed an overall seroprevalence of hepatitis B surface antibodies of 31.1% among Army recruits in 2001, General Leonard Wood Army Community Hospital began universal screening of its basic trainees for hepatitis B immunity before immunization. Before our initiation of serologic screening, all recruits aged 18 years and older received universal immunizationwith bivalent hepatitis A and hepatitis B vaccine (Twinrix; GlaxoSmithKline) as a 3-dose series. Under our screening algorithm, recruits found to be immune to hepatitis B would receive only the monovalent hepatitis A vaccine as a 2-dose series. Between 31 May and 7 July 2005, our facility performed serologic screening for hepatitis B immunity on 2872 recruits aged 18 years and older, of whom 2210 (76.9%) were aged 18–19 years, 319 (11.1%) were aged 20–21 years, 131 (4.6%) were aged 22–23 years, and 212 (7.4%) were aged 24 years and older. Of the 2041 men (71.1%), 1574 were aged 18–19 years, 235 were aged 20–21 years, 85 were aged 22– 23 years, and 147 were aged 24 years and older, composing 71.2%, 73.7%, 64.9%, and 69.3% of their age groups, respectively. Results of serosurveillance were collected for nonresearch purposes, and, therefore, we did not collect other demographic information and do not report results of testing of recruits aged 17 years. Testing for hepatitis B immunity was performed on fresh serum using the Vitros ECi hepatitis B surface antibody quantitative immunometric assay (Ortho-Clinical Diagnostics). Borderline results were treated as negative results. We found an overall rate of immunity in our recruits aged 18 years and older of 57.8%, with age-specific immunity of 61.9% in those aged 18–19 years, 57.4% in those aged 20–21 years, 38.9% in those aged 22–23 years, and 26.9% in those aged 24 years and older. Of note, the recruits aged 22–23 years are members of the birth cohort aged 18–19 years in 2001, in which Scott et al. [1] noted a rate of immunity of 37.0%. Sex-specific rates of immunity and confidence intervals are presented in table 1. Given a per-dose cost to the Army of $30.90 for Twinrix and of $14.83 for monovalent hepatitis A vaccine [4] and a per-screening cost of $5.22 [5], we estimate that, in recruits aged 18 years and older, our screening program will save an average of $31.19/recruit. Serologic screening for hepatitis B immunity should be expanded to other Army training sites and to other military services.