Hepatitis B variant in Europe [letter]

Clinical investigation of children and adults in 2 regions of Italy suggests the emergence of a variant of hepatitis B virus associated with successful immunization. The 885 children who were found to have hepatitis B surface antigenemia had been born to carrier mothers. Antigen was detected in the serum of 625 of these children 14-27 months after completion of immunization with 2 licensed hepatitis B vaccines; the circulating anti-hepatitis B surface titers ranged from 55-370 mIU/ml. Antigen was also noted during the administration of booster doses of the vaccine 4-9 months after the 1st injection; these titers ranged from 70-210 mIU/ml. Similar observations were made in children who had contact during booster immunization with a family member who had hepatitis B and 7-10 months after immunization. The circulating uncomplexed anti-hepatitis B surface antigen had a high titer to the viral group specific determinant a suggesting that the circulating viral antigen has an unusual epitopic conformation and is not neutralized by anti-a surface antibody. Infection with this variant was not associated with clinical illness in the majority of adults and children studied. Longterm follow-up studies should be conducted on this population; however the possibility of additional hepatitis B infections in successfully immunized individuals at high risk of infection seems likely.