The Changing Epidemiology of Acute Hepatitis A in Texas

Background: Hepatitis A vaccine was first required for children entering school in Texas in specific counties in 1999, four years after the vaccine was licensed. Since then, the vaccination requirements have periodically expanded to include more counties and more children. In 2005, hepatitis A vaccination was required for all children attending childcare facilities. For the 2009-10 school year, the requirement was expanded to all children entering kindergarten or attending a childcare facility in Texas.

Objectives: To determine how the epidemiology of hepatitis A has evolved in Texas since the introduction of the vaccine, with special focus on 2008 data to establish a baseline to evaluate the newly established vaccine requirements.

Methods: Descriptive statistics for hepatitis A surveillance data over the last 14 years were analyzed to determine differences in the distribution of hepatitis A in 1995 compared to 2008.

Results: The overall incidence rate (cases per 100,000 population) in 1995 was 16.0 (n=3001) compared to 1.1 in 2008 (n=259). The highest incidence rate occurred in the 5-9 year age range (IR=47.4) in 1995. The incidence rates were lower for each age group in 2008 with the highest incident rate found in the 60+ age range (IR=1.76). Hispanics accounted for 62% of cases in 1995, but only 28% in 2008.

Conclusions: Vaccination strategies thus far have been successful in lowering the incidence of hepatitis A in Texas. Given the success in counties where hepatitis A vaccine has been required for school entry, expansion of this requirement across the state is also projected to help continue to decrease incidence of hepatitis A.