The object of the experimental work on which this thesis is based has been to secure a pertussis vaccine for the active immunisation of children, which will approach more; closely in its immunising potency the living organism acting in a natural, non-fatal attack of the disease.
Pertussis vaccination has advanced remarkably in the last fifteen years and the phase I vaccines now in worldwide use undoubtedly confer a high degree of protection against this major killing disease of infancy. The author believed, however, that phase I of H. pertussis, in terms of the very liberal interpretation given this phase by most workers in this field, does not represent, antigenically, the smoothest phase of the organism available.
Accordingly, a series of experiments was performed during the last three years seeking, firstly, to establish the existence of a more virulent phase of H. pertussis, and, secondly, to convert this phase into a vaccine retaining the maximum of immunising potency.
Both objects have been achieved and the experimental findings are in accord with my theory that virulence is the most reliable index of immunising potency. Two methods of cultivating H. pertussis to produce vaccines superior to the standard phase I vaccines are described, and the results appear sufficiently encouraging to warrant the institution of large-scale field trials involving adequate numbers of vaccinated and non-vaccinated children.
In addition, certain allied problems arising from the main studies, such as that of the efficiency of oral immunisation have been examined and the results recorded. Other problems are receiving further attention.