Immunogenicity and Safety of a 2 + 1 DTPa Priming Schedule in Australian Infants and the Impact of Maternally Derived Antibodies on Pertussis Antibody Responses up to 4 Years of Age.

We assessed the impact of maternally derived pertussis antibodies on infant responses to a 2 + 1 vaccine schedule (6 weeks, 12 weeks, and 12 months). Infants with baseline antibodies showed lower IgG responses following the primary vaccination series, but this did not impair booster responses at 4 years of age. Clinical Trials: The study is registered on the Australian New Zealand Clinical Trials Registry - www.anzctr.org.au (Part 1: ACTRN12615000898550, Part 2: ACTRN12622001216707).