Pertussis vax effectiveness reduced by mutations

Researchers analysed 320 bacteria samples from strains of Bordetella pertussis from patients with whooping cough across Australia during the period 2008–12 and found that many strains no longer produce pertactin, a key surface protein. 

Pertactin is one of three surface proteins present in the whooping cough vaccine used in Australia, along with the pertussis toxin and filamentous haemagglutinin. 

During the period of the study, the proportion of pertactin-free strains rose from 5% of cases in 2008 to 78% in 2012.

Pertactin-free strains have also been detected in Europe and the United States. While there is no evidence that the strains are more harmful or that they reduce vaccine effectiveness, the research suggests the mutated strains have gained selective advantage over strains with the pertactin protein, making it harder for antibodies in vaccinated people to destroy whooping cough bacteria.

Connie Lam, lead author of