A recent study by George N. Ioannou from the Veterans Affairs Puget Sound Health Care System, children as well as adolescents in the US are showing higher rates of immunity against HBV than adults. Data was collected from 39,787 subjects of the National Health and Nutrition Examination Survey to determine the presence of HBV infection, exposure and immunity in the US. Remember that HBsAb suggests immunity either from previous infection or vaccination and HBsAG suggests a diseased individual!
So this study looked at past exposures, prevalence, immunity states and other associations to chronic HBV infection from 1999-2008 using HBsAg and HBsAb as well as core antigen studies, to acquire a complete picture of various patients statuses.
Chronic HBV infection was identified in 0.27 percent of individuals six years old and above. 4.6% had been exposed to HBV. Individuals between the ages of six to nineteen years old had low rates of infection and past exposure. These numbers are lower than past estimates from 1988-1994. Overall, this new study showed immunity in children aged two years to be 68.6%, but much lower rates in adults.
Thus, vaccination of high risk adults must still be emphasized.