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- Categorized in: August 2011, Department of Defense (DoD), Department of Veterans Affairs (VA), Hepatitis
Children Have Higher Rates of Immunity Against HBV
Increased use of HBV vaccine in pediatric settings over the past decade has resulted in a cohort of children and adolescents with a very low prevalence of HBV infection and high rates of immunity. In contrast, adults, including those at high risk for HBV infection, continue to have low rates of immunity against this virus.
These findings were reported in a study that sought to determine up-to-date estimates of infection, exposure, and immunity rates for HBV in the United States population by using data on nearly 37,000 participants from the National Health and Nutrition Examination Survey (NHANES) studies conducted from 1999 to 2008.1
Dr. George N. Ioannou, from the Veterans Affairs Puget Sound Health Care System and University of Washington in Seattle, reported in his paper that among persons aged 6 years or older, 4.6% had been exposed to HBV, according to NHANES data. In contrast, among the same age group surveyed from 1988 to 1994, 5.1% had been exposed to HBV.
Among persons six years and older the prevalence rate of chronic hepatitis B was 0.27% in 1999 to 2008 compared to a 0.42% prevalence in 1988 to 1994. From 1999 to 2008 the prevalence of chronic HBV specifically in children ages 6 to 12 was 0.03%. Prevalence rates climbed with age and peaked at 0.57% for subjects in their 50s. It then decreased down to about 0.20% among older people.
“Other studies suggest that more than one half of the reported cases of acute hepatitis B in the United States occurred in persons who had previously received care in sexually transmitted disease clinics or correctional facilities,” he wrote in his paper. “Taken together with past studies, the current results highlight the need for better mechanisms to both reach and offer vaccination to these high-risk groups.”
A limitation cited in the study was that NHANES neither oversampled nor specifically identified Asian races or ethnicities that have high prevalence of HBV. Another limitation cited in the study was that incarcerated and homeless persons were not sampled.
“If these persons were added to the 704,000 persons that were estimated to have HBV, the total number of persons with chronic infection would increase to 738,000, or 0.28% (instead of 0.27%). Among homeless veterans hospitalized at a Veterans Administration domiciliary from 1995 to 2000 who were also tested for HBV infection, 1.17% had a positive result. The exclusion of homeless and incarcerated persons from NHANES means that the true national HBV prevalence was slightly underestimated,” Ioannou wrote.
The Veterans Affairs Research Enhancement Award Program was the primary funding source of the study.
- Ioannou GN. Hepatitis B virus in the United States: infection, exposure, and immunity rates in a nationally representative survey. Ann Intern Med. 2011 Mar 1;154(5):319-28.
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