Whooping cough in relation to other childhood infections in 1977-9 in the United Kingdom.

Estimates based upon notifications indicate that there was in the 1977-9 triennium in the United Kingdom the largest outbreak of whooping cough for 20 years or more. During this triennium there was also a sharp increase in other infections diseases of childhood, notably in non-notifiable respiratory infections. Isolates of certain respiratory viruses ran in parallel and collectively outnumbered those of Bordetella pertussis during the period of increase in notifications. There was highly significant positive correlation between isolates of B pertussis and of ECHO viruses, of Mycoplasma pneumoniae and rhinoviruses and, in Scotland only, of Coxsackie virus. Deaths in which whooping cough was certified as the immediate of underlying cause were lower than in previous outbreaks. Only a minority were bacteriologically confirmed. A closer study of the outbreak in Glasgow disclosed considerable variations in notification procedure and lack of correlation with isolates of B pertussis at the peak of the notification period. Attack rates calculated from notification were higher in deprived areas. Birth cohort studies showed a significantly higher proportion of notifications in unvaccinated children aged 1-4 and this was confirmed in family studies of clinical whooping cough in home contacts. But, overall, about 35% of reported cases were children who had received three injections of triple vaccine. Acceptance of pertussis vaccine fell sharply in 1975 but about 95% of unvaccinated children in age groups 0-5, including the 1977 and the 1977 and 1978 birth cohorts, either escaped infection or were not notified.