Pertussis: an important target for maternal immunization.

Cord blood antipertussis IgG concentrations were measured in infants and were found to be nearly equal to maternal levels. By 4 months of age most infants had no measurable antibody to pertussis toxin (PT) or filamentous hemagglutinin. Higher concentrations of maternally derived antibody to PT were associated with a weaker pertussis toxin antibody response to whole cell pertussis vaccine, but not to a cellular vaccine. These studies suggest that maternal immunization would provide early protection of the newborn to allow time for the primary immunization schedule at 2, 4, and 6 months of age to induce more durable protection.