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29 Apr 2014

Toddlers may need to get a whooping cough immunisation booster at 18 months amid signs the infection is developing a resistance to current vaccines.

Researchers from the National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases (NCIRSVPD) found that the diphtheria–tetanus–acellular pertussis (DTaP) vaccine provided good protection against whooping cough for the first 12 months, but its effectiveness in children between two and four years of age fell away more sharply than had previously been observed.

The study found almost 80 per cent of whooping cough cases analysed were caused by a mutated bacteria that had stopped producing pertactin – one of the three key proteins targeted by the vaccine.

Study co-author Peter McIntyre told the Sydney Morning Herald the result was “clearly…a red light in terms of how well the vaccination works”.

“Immunisation is still the best and only way to protect against the most extreme cases of the disease ... but the effectiveness is waning and the bug mutation could be contributing to the vaccine wearing off faster.”

AMA President Dr Steve Hambleton said the results were concerning, but said more research needed to be done.

Whooping cough is a potentially deadly infection, particularly for infants, and remains prevalent despite the fact that a vaccine has been available for more than 50 years.

The NCIRSVPD said immunity waned over time and outbreaks typically occurred every three to four years.

The number of cases in Australia has doubled in the past decade, and around 38,000 were infected during the last major epidemic in 2011.

Between 2000 and 2011 there were 25 deaths attributed to pertussis, 18 of which were infants younger than 12 months.

The research was published in the journal Pediatrics.

Adrian Rollins

Published: 29 Apr 2014