Attack rates of notified whooping cough in immunised and unimmunised children.

The incidence of whooping cough among immunised children under the age of six and among children of the same age who were not fully immunised was ascertained by analysing whooping-cough notifications from several health authorities. In the first three years of the study the results showed that attack rates were much higher in children who were not fully immunised than in those who were. This finding suggests that current vaccines provide young children with substantial protection against whooping cough.