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

March 25, 2011

CDC -3-23-11

UNITED STATES: " Hepatitis B Virus in the United States: Infection, Exposure,

and Immunity Rates in a Nationally Representative Survey "

ls of Internal Medicine Vol. 154: P. 319-328 (03.01.11):: N.

Ioannou, BMBCh, MS

" 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, " the author explained. Ioannou

used a nationally representative, cross-sectional household survey to determine

chronic HBV prevalence, associations, past exposure, and immunity in the United

States from 1999 to 2008.

A total of 39,787 participants in the National Health and Nutrition Examination

Survey (1999-2008) ages two years or older were included. Chronic HBV was

defined by presence of serum HBV surface antigen and prior exposure by serum

antibody to hepatitis B core antigen among persons ages six or older. Infant

immunity was defined by presence of serum antibody to hepatitis B surface

antigen among children age two years.

Estimates showed 0.27 percent (95 percent confidence interval, 0.20 percent to

0.34 percent) of persons ages six and older had chronic HBV, or approximately

704,000 people. HBV exposure was indicated in 4.6 percent (CI, 4.1 percent to

5.0 percent) of those surveyed, or approximately 11,993,000 persons. Compared to

earlier US estimates of HBV infection (0.42 percent) and exposure (5.1 percent)

from 1988 to 1994, these estimates are lower (p<0.001). Infection and past

exposure were " very uncommon " among those ages six to 19. While children age two

were found to have high rates of immunity (68.6 percent [CI, 64.1 percent to

73.2 percent]), adults - including those at high infection risk - showed much

lower rates of immunity.

Ioannou noted that the study's limitations included the fact that incarcerated

and homeless persons were not sampled. In addition, categorization of race or

ethnicity did not identify high-risk groups, such as persons of Asian or Pacific

Islander descent.

" 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, " Ioannou

concluded. " Vaccination of high-risk adults should continue to be emphasized. "

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