Healio reported on a study to determine whether adolescents who had received hepatitis B virus (HBV) vaccine as infants retained immunity before and after a challenge dose of vaccine. Amy B. Middleman, MD, MSEd, MPH, editorial board member of Infectious Diseases in Children, and colleagues investigated 420 adolescents ages 16–19 who had received recombinant HBV three-dose vaccine. The researchers divided participants into two groups: group 1 included those who had received vaccine within 7 days of birth; and group 2, those who started the vaccine 4 weeks or more after birth. Participants received either a 10-microgram (mcg) or 20-mcg challenge dose of vaccine. Results show that 92 percent of participants achieved effective seroprotective levels after the challenge dose. Regardless of whether participants had received the 10-mcg or 20-mcg challenge dose, they showed no differences in seroprotection. Group 2 had significantly higher geometric mean titer (GMT) response to the challenge dose compared with group 1. Also, participants who received the 20-mcg dose had higher GMTs than those who received the 10-mcg dose. Higher baseline antibody to HBV titer, older age at first dose of vaccine, higher test dose, nonwhite race, interactions of test dose, and marijuana use were independently associated with higher GMT response to the challenge dose of vaccine. The researchers concluded that the findings and the low incidence of acute HBV in the United States make a booster dose of vaccine seem unnecessary as part of routine immunization for adolescents. The researchers suggest follow-up tests with a similar population 20–25 years after HBV vaccine during infancy to investigate further duration of protection. The full report, “Duration of Protection After Infant Hepatitis B Vaccination Series,” was published in the journal Pediatrics (2014; doi: 10.1542/peds.2013-2940).