Interchangeability of 2 diphtheria-tetanus-acellular pertussis vaccines in infancy.

Objective: Currently, 4 diphtheria-tetanus-acellular pertussis (DTaP) vaccines are licensed for pediatric use in the United States, and 2 are commercially available. Although a single manufacturer's DTaP vaccine should be used for all 3 doses of the primary immunization series, some circumstances result in infants receiving DTaP vaccines from more than 1 manufacturer. The purpose of this study was to evaluate the safety and immunogenicity of a mixed sequence of 2 different DTaP vaccines.