[Reasons of failure in blocking mother-infant transmission of HBV by using vaccine and related strategies].

We have detected the serum marker of HBV of 32 mothers whose HBsAg present positive and their children whom were given Hepatitis B vaccine immunization throughout duration of their mothers' pregnancy, altogether making up 66 cases. In 3 of these 32 families, Hepatitis B vaccine failed to block transmission between mother and infant. Direct nucleotide sequence analysis of HBV were carried out in 7 HBsAg positive infected persons. To confirm the possibility of HBV transmission between mother and infant on molecular level, we used PCR technique and DNA sequencing method. The reasons of which HBV vaccine failed in blocking transmission were discussed at the point of views of virus variation. Besides, we make and emphasized discussion on how to tighten up the measurement of controlling the course of infection and protecting susceptible population.