Most US Teenagers Lack Hepatitis A Immunization

Daniel M. Keller, PhD

January 23, 2012

January 23, 2012 — Most adolescents in the United States lacked immunization for hepatitis A in 2009, leaving them susceptible to hepatitis A infection going into adulthood. In the first study to evaluate hepatitis A vaccine (HepA) coverage in the United States, using data from healthcare providers, researchers from the US Centers for Disease Control and Prevention in Atlanta, Georgia, reported in an article published online January 23 and in the February print issue of Pediatrics that nationally, 1-dose coverage with HepA among adolescents was 42.0%. Of those teenagers who were vaccinated, approximately 70% completed the 2-dose series, which is equivalent to 29.5% of the entire cohort of adolescents surveyed.

Using data from the 2009 National Immunization Survey-Teen (N = 20,066) to determine HepA coverage among 13- to 17-year-olds, Christina Dorell, MD, MPH, and coauthors found that among states in which the Advisory Committee on Immunization Practices (ACIP) has recommended universal child vaccination at 2 years since 1999 (group 1), 1-dose coverage was 74.3%. Among states with an ACIP recommendation for consideration for child vaccination at 2 years since 1999 (group 2), the rate was 54.0%, and among states with a recommendation of universal child vaccination at 1 year of age since 2006 (group 3), the rate was 27.8%.

The researchers noted that 1 dose of vaccine induces protective levels of antibodies in more than 97% of infants and children, and a second dose is thought to confer long-lasting immunity.

The study determined HepA coverage estimates through data provided by healthcare providers. Only adolescents with sufficient data to determine vaccination status were included in the study. The adolescents in the study were born between 1991 and 1997, and the investigators listed HepA coverage for every state and the District of Columbia.

For all 3 groups, one of the strongest factors for initiating HepA was having a recommendation from a healthcare provider, but only 25.0% of the sample reported receiving such a recommendation. For groups 1 and 2, American Indian/Alaska Native, Hispanic, black, or Asian ethnicity was an independent predictor of higher HepA coverage. The authors proposed that because of traditionally higher rates of hepatitis A disease among these populations, efforts focused on encouraging vaccination were likely successful.

For groups 2 and 3, the metropolitan statistical area independently predicted HepA initiation, with adolescents in rural areas less likely to be vaccinated compared with those in urban areas. The authors noted that the pediatrician-to-child ratio is higher in urban areas, so urban adolescents are more likely to be seen by pediatricians. "Higher pediatrician concentrations have correlated with increased vaccination among children," the authors write.

Previous studies have shown that information, assurances, and recommendations from healthcare providers increase parental acceptance of vaccination. However, provider concerns about reimbursement and the perception by some providers that hepatitis A is not a significant health problem may lessen the chances that they will recommend the vaccine. Therefore, the study investigators recommend continuing education of providers about the severity of hepatitis A infection and the safety and efficacy of the vaccine.

A limitation of the study is that the National Immunization Survey-Teen begins with a random-digit-dialed survey limited to households with landline telephones. (Surveys are then mailed to all vaccination providers of parent/guardian telephone respondents who consent to participate.) Therefore, the survey may not be representative of households without landline telephones. Second, recall bias may affect parents' reports of receiving a recommendation for vaccination.

Because hepatitis A virus is highly infectious and will probably continue to be introduced to the United States through imported food, international travel, international adoption, and other means, the authors recommend continued vaccination of adolescents to protect them during this period, and as they mature into adults. In this way, the prevalence of significant hepatitis A disease may be minimized, lowering morbidity, hospitalizations, lost work, and the large expense of containment efforts.

The authors have disclosed no relevant financial relationships.

Pediatrics. 2012;129:213-221. Abstract

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