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.
Dr George Ioannou from Washington, USA determined the prevalence and associations of chronic hepatitis B virus infection, past exposure, and immunity in the United States from 1999 to 2008.
The research team performed a nationally representative, cross-sectional household survey in a civilian, noninstitutionalized population in the USA.
The researchers evaluated 39,787 participants in the National Health and Nutrition Examination Survey aged 2 years or older.
|5% had been exposed to hepatitis B virus|
|Annals of Internal Medicine|
Chronic hepatitis B virus 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.
Among persons aged 6 years or older, 0.3% had chronic Hepatitis B virus infection, and 5% had been exposed to hepatitis B virus.
The researchers noted that these estimates are lower than estimates of hepatitis B virus infection, and exposure in the United States reported from 1988 to 1994.
Infection and past exposure were very uncommon among persons aged 6 to 19 years.
The research team found that children aged 2 years have high rates of immunity.
Adults, including those at high risk for infection, have much lower rates of immunity.
The researchers reported that incarcerated and homeless persons were not sampled.
The team observed that categorization of race or ethnicity did not identify high-risk groups, such as persons of Asian and Pacific Islander descent.
Dr Ioannou's team concludes, "A cohort of children and adolescents is growing up in the United States with high rates of immunity against hepatitis B virus and very low rates of infection."
"Vaccination of high-risk adults should continue to be emphasized."