British Medical Journal
19 July 2014(vol 349, issue 7967)
We need to act now, not wait for longer lasting new vaccines
Pertussis (whooping cough) continues to be a major cause of morbidity and mortality throughout the world and is one of the leading causes of deaths from vaccine preventable diseases. In recent years, large outbreaks of pertussis have been reported in many developed countries, despite widespread use of vaccines.1 2…
…There is uncertainty about the causes of the apparent resurgence of pertussis. Possible contributors include more sensitive and more readily available methods for diagnosis; enhanced awareness and more complete reporting; decreased duration of adaptive immunity after immunization with acellular vaccines (compared with whole cell vaccines), perhaps related to a decreased T helper type 1 immune response; and mismatch between the antigens in the acellular vaccines and those of circulating strains of B pertussis. Although the largest increase in reported incidence seems to be in adolescents, children aged <3 months are at highest risk of serious morbidity and mortality from pertussis.
Immunity to pertussis, whether vaccine induced or from natural infection, is not life long. So there is a large pool of susceptible adults and adolescents to serve as a reservoir for pertussis in the community. There is now substantial evidence, however, that immunity induced by acellular pertussis vaccines, which in many countries have replaced the more reactogenic whole cell vaccines, wanes most rapidly.6…
…Modifications of current vaccines might also help in the near term. If formulations of acellular pertussis vaccines were available without other components, such as diphtheria toxoid or inactivated polio vaccine, it might encourage recommendations for more frequent booster doses of pertussis vaccine to reduce the pool of susceptible persons. Improving the immune response by adding extra antigens of B pertussis to existing vaccines, changing adjuvants, or adding new ones could be another short term solution.
However, there is general agreement that new and more durable vaccines are needed.12 Unfortunately, development and licensure of such new products require a substantial investment of money and time. Examples of such longer term solutions include new live attenuated vaccines that could be administered intranasally or perhaps a genetically engineered vaccine that uses bacteria, viruses, or other vehicles to deliver bacterial antigens. It is clear that we need redoubled efforts to combat the real, persistent, and potentially lethal threat of pertussis.
Whooping cough in school age children presenting with persistent cough in UK primary care after introduction of the preschool pertussis booster vaccination: prospective cohort study
BMJ 2014;348:g3668 (Published 24 June 2014)
Safety of pertussis vaccination in pregnant women in UK: observational study
BMJ 2014;349:g4219 (Published 11 July 2014)