A single dose of an effective whole cell pertussis vaccine does not significantly increase protection in children primed with a less effective vaccine

Abstract We evaluated if a single dose of a protective whole cell pertussis vaccine given before school entry to children primed with a less effective vaccine would increase their protection. A school cohort including 3876 students and a family cohort including 162 children were assessed. Although there was a trend toward increased protection, the better vaccine did not provide a significant improvement. These results suggest that a single dose of an effective vaccine given to children primed with a less effective one does not raise the protection to a level similar to that provided by three doses of the better vaccine.