The implication of a reduced-dose hepatitis B vaccination schedule in low risk newborns.

Five hundred and seventy-four babies born to HBsAg negative mothers in Hong Kong received either a regular (5 micro g) or reduced (2.5 micro g) three-dose regimen of recombinant hepatitis B vaccine. A significantly higher anti-HBs positivity rate (>or=10 mIU/ml), geometric mean titer (GMT) and the maintenance of a high anti-HBs level (>or=100 mIU/ml) were observed with the regular-dose regimen. The differences persisted, however, only up to 1 year post-vaccination. Over an 8-year period, only 1% of the vaccinees demonstrated anti-HBc seroconversion and none had become HBsAg positive. The long-term efficacy of the reduced-dose regimen was confirmed, even in an HBV endemic population.