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

March 4, 2011

Original Research

Hepatitis B Virus in the United States: Infection, Exposure, and Immunity Rates

in a Nationally Representative Survey

N. Ioannou, BMBCh, MS

+ Author Affiliations

From Veterans Affairs Puget Sound Health Care System and University of

Washington, Seattle, Washington.

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.

March 4, 2011