By Michael Smith, North American Correspondent, MedPage Today
Most babies born to mothers with hepatitis B (HBV) appear to get post-exposure prophylaxis as well as the full three-dose series of vaccine against the virus, the CDC is reporting.
But adherence to a key follow-up step – post-vaccination serologic testing – seems less complete, the agency reported in the Sept. 28 issue of Morbidity and Mortality Weekly Report.
About 25,000 infants are born every year in the U.S. to mothers who test positive for the hepatitis B surface antigen (HBsAg), the CDC report noted, and without intervention up to 90% of infants can become infected, increasing their risk for cirrhosis or early death.
For that reason, the CDC’s Advisory Committee on Immunization Practices urges post-exposure prophylaxis with hepatitis B vaccine and hepatitis B immune globulin within 12 hours of birth. Exposed infants should also complete the three-dose HBV vaccine series.
To evaluate the effect of the treatment, the committee has recommended, babies should be tested – a month after the last dose of vaccine — for the HBV surface antigen and for the antibodies against it.
To see how well those recommendations were being carried out, the agency studied outcomes at 24 months for babies whose HBV-positive mothers were enrolled during 2008–2009 in five Enhanced Perinatal Hepatitis B Case Management Projects.
All told, the five projects — in Florida, Michigan, Minnesota, New York City, and Texas — managed 5,075 infants, of whom 4,214 had been given at least three doses of HBV vaccine by the age of 24 months.
But post-vaccination serologic testing took place in only 3,244 children (77%) of those who got their three shots.
Of those, the CDC analysis found, the testing was incomplete in 412, including 41 tested only for antibodies and 371 tested only for the surface antigen.
The date of testing was not reported for 561 children.
Of the 2,683 children with both testing and dates reported, the agency found, 93.3% were protected, 3.2% remained susceptible but were not infected, and 1.2% were infected. The remaining 2.3% had indeterminate results.
The rates of post-vaccination serologic testing have been rising, the agency noted – in one study from about 25% in 1994 to 56% in 2008.
But “this analysis highlights areas in need of improvement,” the CDC report said, adding that strategies are needed to increase overall testing rates, as well as complete testing for both antibodies and the surface antigen, which are needed to confirm outcomes.
The study, the agency report cautioned, is based on five HBV perinatal case management projects and might not be representative of all births to women with HBV infection.
The analysis was conducted by the CDC and state and local health departments. The authors are employees of those agencies.
Primary source: Morbidity and Mortality Weekly Report
Centers for Disease Control and Prevention “Postvaccination Serologic Testing Results for Infants Aged ≤24 Months Exposed to Hepatitis B Virus at Birth — United States, 2008–2011” MMWR 2012; 61: 768-77
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