Hepatitis B Virus in the United States: Infection, Exposure, and Immunity Rates in a Nationally Representative Survey


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Abstract

Background:Up-to-date estimates of the prevalence of hepatitis B virus (HBV) infection, exposure, and immunity are necessary to assess the effectiveness of ongoing programs aimed at preventing HBV transmission.Objective:To determine the prevalence and associations of chronic HBV infection, past exposure, and immunity in the United States from 1999 to 2008.Design:Nationally representative, cross-sectional household survey.Setting:U.S. civilian, noninstitutionalized population.Participants:39 787 participants in the National Health and Nutrition Examination Survey (1999 to 2008) aged 2 years or older.Measurements:Chronic HBV infection was defined by presence of serum HBV surface antigen and past exposure by serum antibody to hepatitis B core antigen among persons aged 6 years or older. Infant immunity was defined by presence of serum antibody to hepatitis B surface antigen among children aged 2 years.Results:Among persons aged 6 years or older, 0.27% (95% CI, 0.20% to 0.34%) had chronic HBV infection (corresponding to approximately 704 000 persons nationwide), and 4.6% (CI, 4.1% to 5.0%) had been exposed to HBV (approximately 11 993 000 persons). These estimates are lower (P < 0.001) than estimates of HBV infection (0.42%) and exposure (5.1%) in the United States reported from 1988 to 1994. Infection and past exposure were very uncommon among persons aged 6 to 19 years. Children aged 2 years have high rates of immunity (68.6% [CI, 64.1% to 73.2%]). Adults, including those at high risk for infection, have much lower rates of immunity.Limitations:Incarcerated and homeless persons were not sampled. Categorization of race or ethnicity did not identify high-risk groups, such as persons of Asian and Pacific Islander descent.Conclusion:A cohort of children and adolescents is growing up in the United States with high rates of immunity against HBV and very low rates of infection. Vaccination of high-risk adults should continue to be emphasized.Primary Funding Source:The Veterans Affairs Research Enhancement Award Program.

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