Protection conferred by the hepatitis B vaccine may wane over time, according to a new study published in the August issue of Pediatrics. Although it is not known how long the HBV vaccine provides protection, researchers decided to measure the immune response indirectly by testing the response to a booster dose of vaccine in 378 healthy children who had been vaccinated in infancy. Results showed that the older the child, the more likely their immunity was waning: 97% of 5-year-olds had an antibody response compared with 60% of 14-year-olds. The findings do not mean that vaccinated children are at greater risk for HBV infection; however researchers are continuing the study to make sure that there isn’t an increase in infections among people vaccinated as young children. Differences in Response to a Hepatitis B Vaccine Booster Dose Among Alaskan Children and Adolescents Vaccinated During Infancy, Pediatrics Vol. 120 No. 2 August 2007, pp. e373-e381@ http://pediatrics.aappublications.org/cgi/content/full/120/2/e373.