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Learning Objectives for this Presentation:
By the end of the presentation participants will be able to:
1. Describe the temporal relationship between the introduction of hepatitis A vaccine in Arizona and the decrease in disease incidence.
2. Draw interim conclusions about the effectiveness of targeting specific populations.
Background:
Before the introduction of the hepatitis A vaccine in 1995, hepatitis A followed a cyclical pattern of increased incidence every 5-10 years in the U.S. The incidence in the American Indian/Alaska Native (AI/AN) population was as much as five times the national incidence. In Arizona, the Indian Health Services (IHS) was an early adopter of the new vaccine, starting widespread vaccination of 2-12 year-old AI/AN children in 1996. Arizona continued to see a relatively high rate of hepatitis A in other sub-populations, and in 1998, hepatitis A vaccine was made available for all children 2-5 years. Hepatitis A immunization was mandated in 1998 for entry to licensed childcare in Maricopa County (which includes metropolitan Phoenix).
Methods:
Hepatitis A incidence and hepatitis A immunization rates were studied for each county for the period 1984 to 2004.
Results:
Dramatic reductions in hepatitis A incidence followed the introduction of the vaccine to specific target groups. Very few cases of hepatitis A have been reported in the past five years from the counties with the largest AI/AN population, which had the highest incidence rates in 1994. Furthermore, although vaccinations in Maricopa County and Native American communities are targeted at young children, incidence rates also declined significantly in adults. Overall, jurisdictions with specific vaccine recommendation programs demonstrated a larger proportional decrease in cases than other areas.
Conclusions:
Hepatitis A vaccine recommendations were effectively implemented by public health services (IHS and county) in Arizona and are currently associated with a striking decline in disease incidence. However, due to the cyclic history of this disease, continuing study is warranted.
See more of E1 - Childhood Hepatitis A Epidemiology and Prevention
See more of The 2005 National Viral Hepatitis Prevention Conference