Whooping cough is a vaccine-preventable disease that has the potential to cause significant morbidity and mortality in unvaccinated individuals. Despite the success of the vaccine there are recent reports of disease in older adolescents and young children who have been vaccinated and the causes for these failures are unknown but are likely to stem from our poor understanding of exactly which components of the bacteria causing the disease (B. pertussis) should be targeted. The ALSPAC team have recently published a study demonstrating that genetic differences in a key region of the human genome, the human leukocyte antigen (HLA) complex, may be associated with differential susceptibility to whooping cough. We have similarly undertaken a genetic study of African children finding associations across the same region of HLA with differential response to three different parts of the whooping cough vaccine. We would like to use sophisticated genetic techniques to compare our results with those from ALSPAC to determine whether we can show that reponses to one or several vaccine components is related to whooping cough susceptibility. These results will enable us to understand why the vaccine is failing in some groups of individuals and how we can improve the vaccine for multiple populations in the future.