Immunisation against whooping cough

Not surprisingly they identified that children who received the whole-cell vaccine were less likely to get whooping cough.

A number of factors could contribute to the results of this study:

• Technology that tests for pertussis infection has improved significantly since the whole-cell vaccine was used in Australia, and New Zealand, and an increase in the number of laboratory diagnosed cases may reflect better identification of the disease now than back then.
• The whole-cell vaccine, used overseas as part of the World Health Organization Expanded Programme on Immunization, generates a very robust immune response that can be associated with noticeable injection site reactions, high fevers and hours of persistent screaming. New Zealand, Australia, the UK and US moved to using the acellular pertussis vaccine to reduce the risk of these unpleasant and, for parents, often frightening and unacceptable vaccine responses. However, a less reactive vaccine also means a reduction in the immune response when compared with the whole-cell vaccine.
• It is possible that over time there have been small changes in characteristics of the pertussis bacteria and the current acellular pertussis vaccine is still effective against much of the bacteria's characteristics but is less effective against the changed ones.
• Pertussis remains highly infectious and no matter how immunity is acquired i.e. through whole-cell immunisation, acellular pertussis immunisation or actually having the wild type disease, immunity wanes over time and controlling the disease remains a significant challenge.

The key messages are:

• The acellular pertussis vaccine still has a protective effect and it is important for infants to receive their National Immunisation Schedule vaccines on time at 6 weeks, 3 months and 5 months of age.
• Parents and people in close contact with infants less than one year of age should have their immunity against pertussis boosted by immunisation to reduce the risk they will infect a vulnerable infant.