Conference Coverage

DTPa-HBV-IPV/Hib in infancy maintains lasting immune memory against HBV in teens



– Four doses of hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenza type b vaccine given in infancy provides reassuringly long-lasting immune memory against hepatitis B among 14- to 15-year-olds, Tino F. Schwarz, MD, reported at the annual meeting of the European Society for Paediatric Infectious Diseases.

Dr. Tino F. Schwarz

Dr. Tino F. Schwarz

He presented the fourth and final study in a series evaluating the antibody persistence and immune memory against hepatitis B (HBV) in recipients of the complete four-dose series of hexavalent DTPa-HBV-IPV/Hib vaccine in infancy. Because exposure to HBV can increase during adolescence, it was essential to determine whether antibody persistence is maintained, explained Dr. Schwarz of Juliusspital Hospital in Wurzburg, Germany.

“As expected, we saw a decrease in anti-HBs [hepatitis B surface antigen] antibody levels over the years, with persistent seroprotection in 85% of children at age 4-5 years, 72% at 7-8 years, 61% at 12-13 years, and now 54% of adolescents at 14-15 years. But we could demonstrate a very strong anamnestic response in the trial. This is good information. It clearly shows that, in patients who are exposed to hepatitis B, we can certainly guarantee that they are protected. It’s a good result for public health. The vaccine is a very robust vaccine which induces a very strong response over the years. It can be boosted, but from an immunologic point of view it is not required,” he said.

The multicenter study included 268 adolescents aged 14-15 years who had received the four-dose hexavalent vaccine series in infancy. Their antibody persistence against anti-HBs was measured, then measured once again 1 month after receiving a challenge dose of monovalent HBV vaccine.

Prechallenge, 105 of the teens were seronegative, 144 were seroprotected as defined by an anti-HBs concentration of at least 10 mIU/mL, and 19 had low seropositivity marked by an antibody level of 6 to less than 10 mIU/mL. Yet 1 month after the booster, which was intended to mimic the impact of real-world exposure to HBV, 83% of the initially seronegative subjects had an anti-HBs concentration of 10 mIU/mL or more, and 67% of them had a level of at least 100 mIU/mL.

“We saw a clear fantastic anamnestic response,” Dr. Schwarz declared.

Overall, 93% of study participants seroconverted, and 87% of them had anti-HBs titers of 100 mIU/mL, “which is the level we’d like to achieve in vaccinees,” he observed.

The booster monovalent HBV vaccine was well tolerated, with one-third of subjects complaining of mild local injection site pain and 30% noting fatigue. But in response to a question posed by session chair Ronald de Groot, MD, emeritus professor of pediatrics at Radboud University in Nijmegen, the Netherlands, Dr. Schwarz said these study results indicate there’s no need for routine boosting in healthy adolescents such as those in the trial. Immunocompromised individuals might be a different story, but they weren’t investigated.

But what about in physicians and surgeons, where protection against HBV infection is essential? Dr. de Groot asked.

“In Germany, we require a titer of 100 mIU/mL or more in medical staff, but we’re quite alone in Europe. Other countries do not require booster vaccination for medical staff. The data we’ve shown here is quite reassuring: If you get exposed, you in effect get a booster. It’s complicated to test surgeons in their offices; better to just rely on the anamnestic response that we’ve demonstrated,” Dr. Schwarz replied.

He reported serving as a consultant to GlaxoSmithKline, which funded the study, as well as to Pfizer and Sanofi Pasteur.

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