Antibody response to hepatitis B immunization in infants born to HIV-infected mothers

To determine the antibody response of hepatitis B immunization begun at birth in HIV-1 exposed infants.

Prospective, clinical trial. SITE: King Chulalongkorn Memorial Hospital, Bangkok, Thailand.

Seventy six infants born to HIV-1 seropositive mothers, who were not hepatitis B carriers, received three 10 microgram doses of recombinant DNA hepatitis B vaccine (Engerix B, Smith Kline, Belgium) in a 0, 1 and 6 month schedule. The first dose was given at birth. Serum hepatitis B surface antibody (Anti -HBs) was measured at age 3, 9 and 12 months. Anti-HBs levels were determined by enzyme-linked immunoassay using the commercial kits (AUSAB EIA diagnostic kits, Abbott Laboratories, Chicago, USA) Antibody titer > or = 10 mIU/ml was defined as seroconversion. HIV infection was diagnosed by a positive test of HIV antibody at age > or = 18 months and/or by positive test of HIV polymerase chain reaction at age > or = 3 months.

There were 14 HIV-1 infected (group 1) and 62 HIV-1 non infected (group 2) infants enrolled in this study. Anti-HBs titers of group 1 infants were significantly lower than those of groups 2 infants at both 3 and 6 months after the 3rd dose of vaccine, (Mann Whitney U test, p=0.019 and 0.001 respectively). Ten infants in group 1 and 57 infants in group 2 had anti-HBs titer > or = 10 mIU/ml. Their peak antibody titers were also noted at both 3 and 6 months after the 3rd dose of vaccine. Seroconversion rates were 71.4 per cent and 91.9 per cent in group 1 and 2 infants respectively, (p<0.05). Among the infants who had blood tests performed at age 12 months or 6 months after the 3rd dose of vaccine, anti-HBs titers declined in approximately 50 per cent of both groups of infants. There was a significantly higher percentage of seroconverters in group 1 who lost their protective titers than those in group 2, (p<0.001).

The results in this study suggested that HIV-1 infected infants have poor antibody response to hepatitis B immunization and the protection was less durable. A fourth dose of vaccine at 6 months after the 3rd dose may be necessary.