Maternal immunization to prevent infectious diseases in the neonate or infant.

The approach of providing passive protection to young infants by immunizing pregnant women can bypass the problems of immunological immaturity in the neonate, avoid or delay active immunization of the infant in the first year of life, and prevent transmission of an infection from the mother to the neonate. Optimal vaccines for this approach should induce high immunoglobulin G antibody titers that quickly reach their maximum level after immunization and persist at protective levels for several years, thus providing passive protection in subsequent pregnancies. Specific applications of this approach include the worldwide practice of maternal immunization with tetanus toxoid vaccine and ongoing studies of maternal immunization to prevent Haemophilus influenzae type b, group B streptococcal, pneumococcal, meningococcal, and human immunodeficiency virus infection in the infant. Addressing the cultural, sociological, and legal aspects of maternal immunization will be required to ensure the success of this approach.