Whooping cough after stopping pertussis immunisation.

An epidemic of whooping cough occurred in a rural practice in Shetland, containing 144 children under 16. Before July 1974 all children were immunised against pertussis, but after that date immunisation was stopped. Of the 134 children studied, 93 had been immunised. Sixty-five of the children developed whooping cough. The incidence of infection was similar in those who had and had not been immunised. The incidence was also similar in those born before and after July 1974. There was no evidence to support the routine use of pertussis immunisation in rural Shetland.     

Whooping cough morbidity and inoculation status

The analysis of pertussis morbidity and the state of immunity to pertussis has made it possible to evaluate the existing epidemiological situation as unfavorable. The restraining influence of specific prophylaxis on the epidemic process of pertussis becomes weaker due to the growing number of nonimmunized children; for this reason, the maximum morbidity rate in pertussis is observed among children under 5 years of age, as it was at the period before the introduction of mass immunization against pertussis. To prevent further possible increase in the intensity of the epidemic process of pertussis and in the severity of the clinical course of the disease, the number of children under 3 years of age, not immunized against pertussis, must be reduced by limiting the number of children exempted from immunization on medical grounds and by increasing the proportion of children immunized from the age of 3 months.