LONG-TERM EFFICACY OF RECOMBINANT HEPATITIS-B VACCINE AND RISK OF NATURAL INFECTION IN INFANTS BORN TO MOTHERS WITH HEPATITIS-B E-ANTIGEN

To evaluate the long-term protection afforded by the vaccine, recombinant hepatitis B (HE) vaccine was given to 171 infants born to hepatitis B e antigen-positive carrier mothers, Group A (53 infants) and group B (57 infants) received four doses of HB vaccine at birth and at 1, 2, and 12 months of age, with a dose of 20 mu g in group A and 10 mu g in group B. Group C (61 infants) received three 20 mu g doses of HB vaccine at birth and at 1 and 6 months of age, These children were followed up annually up to 5 years of age, Six children (4%) became HB carriers before 1 year of age, and the carrier state persisted to the end of follow-up, The overall seropositive rate of HB surface antibody (anti-HBs) dropped from 99% at 1 year of age to 83% at 5 years of age. Among 548 serum pairs taken at 1-year intervals from children negative for HE surface antigen (HBsAg), a fourfold rise of anti-HBs titer was noted in 58 (11%) and a 10-fold rise of anti-HBs was noted in 17 (3%), Maternal HE core antibody disappeared in most children (151/152, 99%) before 2 years of age, Natural infections, as judged by persistence or reappearance of HE core antibody, occurred in 19 of 163 (12%) HBsAg-negative children. None of these episodes was associated with HBsAg positivity, We conclude that the long-term protection afforded by recombinant HB vaccine is satisfactory and that a further booster dose before 5 years of age is not necessary.