The Effectiveness of Pertussis Immunisation in Children (EPIC) study data provides good evidence that the current National Immunisation Schedule protects against severe pertussis in infants and children.

The pertussis vaccine provides moderate protection against severe disease after two doses and good protection after three doses. No evidence of waning immunity was shown following dose three up to age four years or following 3P+1 doses up to age seven years.

Further investigations are required to investigate protection against mild disease and duration of protection in older children and adolescents, and to evaluate the effects of delays between doses one and three.