Protection after combine passive-active immunisation against hepatitis B was investigated in 578 neonates of HBsAg positive mothers. All mothers were HBsAg positive during pregnancy, 30 of them (5%) were also HBeAg positive. The number of newborns gradually increased since 1988 and the children were immunised according to schedules valid in the Czech Republic. The children received three 10 microgram HBsAg doses of plasma-derived or recombinant vaccine in majority children at 0, 1 and 6 months of life, only in 21 children of HBeAg positive mothers at 0, 1 and 2months and in 17 children at 3, 4 and 9 months. The children received 50 or 100 international units of hepatitis B immunoglobulin at birth, only 17 children received next two doses of hepatitis B immunoglobulin at 6 and 13 weeks. The immunisation schedules were completed in 555 children. Anti-HBs antibodies were tested in 541 children after immunisation; protective titres of anti-HBs were proved in 508 of them (94%). Vanishing of protective anti-HBs antibodies was detected in 30%, 49% and 62% children in 5, 10 and 13 years of their life. Vertical transmission of hepatitis B virus with chronic HBsAg carrier status was proved only in 2 children. One child was infected by escape mutant with substitutions of HBsAg at residues 137 and 139. Asymptomatic infections with presence of anti-HBc antibodies were observed in 5 children since fourth till fifteenth year of life. The anamnestic response with double increase of anti-HBs without revaccination was observed in 36 children. The vaccination of newborns of HBsAg positive mothers against hepatitis B practically interrupted the vertical transmission of hepatitis B virus in the Czech Republic.

        Key words: viral hepatitis B, vaccination of newborns, HBsAg, anti-HBs, anti-HBc