A Comparison of Immunogenicity of Reduced Doses of Hepatitis B Vaccine in Infants Born to Noncarrier Mothers in Taiwan

To compare the immunogenic effect of a reduced dose of hepatitis B vaccine in infants born to noncarrier mothers, we randomly divided 298 infants into 3 groups to receive 3 different doses of 5 μg (group A: 101 infants), 2μg (group B: 99 infants) and l μg (group C: 98 infants) of Pasteur plasma vaccine. The immunization protocol involved 3 injections of vaccine starting within one week after birth at one month intervals, and a booster at one year. At six months, infants of group A had significant increased rate of anti-HBs response rate (96%) when they compared with group B (85%) and group C (76%). Seven percent of vaccinees lost their antibody before booster, but it rose rapidly to 97, 92, and 88% respectively in group A, B and C at 2 months after booster injection. The geometric mean titers of anti-HBs was significantly higher in group A responders as compared to group B and C at ages of 6, 12, and 14 months. This study shows that standard 4 doses 5 µg Pasteur hepatitis B vaccine is most appropriate for mass immunization of infants born to noncarrier mothers in Taiwan. No adverse reactions were observed.