Vaccination of newborns against hepatitis A in the presence of maternally derived antibodies.

Infection by hepatitis A virus (HAV) is a significant cause of childhood disease but effective vaccines are available. Naturally acquired anti-HAV antibodies ensure transfer of protective immunity which persists for up to 6 months in the newborn. Such maternal anti-HAV antibodies are able to inhibit the antibody responses in infants vaccinated with inactivated hepatitis A vaccines, although no clinically significant consequences of this are observed. By increasing the number of doses, for example by using a three dose primary vaccination schedule, and by increasing the amount of vaccinal antigen, this interfering effect may be partially overcome.