Hepatitis B virus infection assessed 3 to 18 years after vaccination in Cuban children and adolescents born to HBsAg-positive mothers.

Thirty-two participants, aged between 3-18 years, born to hepatitis B surface antigen (HBsAg)-positive mothers and vaccinated at birth were analyzed for hepatitis B virus (HBV) infection. Overall, 56% had anti-HB titers >/=10 IU/L; five were positive for antibodies to the core antigen (anti-HBc), and two of these were also positive for HBsAg/DNA. One of the HBsAg/anti-HBc double-negative children presented with an unusual occult infection (HBV DNA-positive). No known vaccine escape mutations were detectable. Our data suggest that the vaccine protected 93.8% of children in this high-risk group against chronic HBV infection. Occult infections should be considered even in countries with low endemicity and high vaccination coverage.