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How protective is the whooping cough vaccine?

Even though Australia has high vaccination rates against whooping cough, we have the highest recorded incidence of whooping cough in the world. Whooping cough is mild in vaccinated children and adults, but young babies who have not yet been vaccinated get seriously ill and sometimes die. Some experts think that the current vaccine, which replaced the original vaccine about 20 years ago because it has fewer side effects, may not be as effective in protecting us long-term from whooping cough. The reasons for this aren't clear, but understanding why this happens may help to improve the vaccine and reduce the incidence of whooping cough in our community.

We are currently studying whether a booster vaccination in adults is necessary to increase long term immunity to whooping cough by comparing the immunity of healthcare workers who have had a booster vaccination in the previous 7-10 years, to healthcare workers who have not been vaccinated since childhood.

Maternal vaccination during pregnancy is very effective in protecting young babies against whooping cough, but it is possible that maternal vaccination may reduce the baby's own response to the whooping cough vaccine. This study will compare immune responses, after receiving their routine vaccinations at 6-8 weeks, and 4 and 6 months, in babies born to mothers who have or have not received a whooping cough booster vaccination. The study will also compare the rate of vaccine reactions in both groups of babies.

Vaccination and allergy

Allergic conditions, particularly food allergies, have become much more common and more severe in the last 20 years. These conditions arise because the affected child's immune system is over-sensitive, and produces a much stronger response to environmental triggers than would normally be expected. Why this hyper-sensitivity should be occurring in so many more children than in previous generations is not known.

Food and other allergies appear to have increased since the phasing out of the original whooping cough vaccine in the late 1990s. The type of immune response to the two vaccines is markedly different, leading some researchers to propose that the original vaccine may have had a protective effect against developing food and other allergies. We are examining this in two different studies.

In the first study, we will look at the health records of children born in the late 1990s and compare the rate of food allergies in children who were vaccinated with the current whooping cough vaccine with those who received the original vaccine. If there is a lower rate of food allergies in the group that only received the original vaccine, it will provide evidence of a protective effect that we can investigate further.

In the second study, we are testing the theory that one dose of the original vaccine at 6-8 weeks of age may reduce the risk of developing food allergies. This study will compare two groups of babies - one group who will receive the current standard vaccine schedule, and the other who will receive a dose of the original vaccine at 6-8 weeks of age and then the standard vaccination schedule after that. We will examine whether the original vaccine is safe and acceptable to mothers, and if there are fewer cases of allergy in that group.