Towards third-generation whooping cough vaccines.

To date, the most significant use of recombinant-DNA technologies has been to hyperproduce natural molecules that are difficult to obtain in large quantities by conventional methods. However, genetic manipulation can also be an efficient way to modify the properties of natural molecules in order to make them more suitable for human use. In the development of third-generation whooping cough vaccines, recombinant-DNA methods were used to remove the enzymatic activity of pertussis toxin in order to obtain a new molecule which is devoid of toxicity, and can be used for safer vaccination against this disease.     

Severity of notified whooping cough.

An analysis was made of the severity of over 8000 cases of whooping cough notified from October 1974 to March 1975. Ten per cent of these patients were admitted to hospital and there were 10 deaths. Severity was directly related to age, the disease being most severe in children under 1 year, especially those under 6 months. There was some evidence that previous vaccination reduced the severity of the disease, but the vaccination programme does not cover very young children, and for them whooping cough is a dangerous disease.     

Effect of vaccination on severity and dissemination of whooping cough.

A study was undertaken in general practice to clarify those factors, especially vaccinations, that influence the clinical picture and infectivity of whooping cough in the community. Although the range of the disease encountered was fairly mild, its duration was notable (mean +/- SD 50.9 +/- 32.1 days). By using multiway contingency table analysis it was found that in the more severe cases of whooping cough vaccination significantly shortened the illness (p less than 0.005) and reduced the number of coughing spasms (p less than 0.025). The protective effect of the vaccine was most notable in modifying infectivity within the family: 19% of vaccinated family contacts of index patients in whom the disease had been confirmed bacteriologically developed the disease when exposed to it compared with 72% of non-vaccinated contacts (p less than 0.001). These results show that whooping cough vaccination modifies the clinical illness and offers a worthwhile degree of protection to children exposed to the disease.