There appears to be a rise in cases of measles among people who have been vaccinated.

Research into measles cases in Victoria has revealed a number of people who were hospitalised with the disease had been vaccinated at least once in the past, but their immunity waned.

The research found that between 2014 and 2017, a small number of measles cases (13) had what is called secondary vaccine failure, meaning they had at least one dose of the vaccine and showed antibodies in their blood, but that protection waned and they contracted measles.

The Royal Melbourne Hospital’s Dr Katherine Gibney says that because Australia has done such a good job at eliminating measles, people who have had only one vaccine are not getting a natural immunity boost as the disease is not circulating in the community.

“If you had been vaccinated and came into contact with someone with measles you might get a little natural boost in your antibody levels,” she said.

“Overall, in countries that have eliminated measles transmission, this is likely to emerge as a problem. There isn’t going to be an enormous number of cases, but it will be important in terms of recognising measles, because the cases are a bit different to those who aren’t immune.”

While these cases were hospitalised, the symptoms were not considered ‘classic measles’, as patients were not reporting fever, cough and runny nose, but they did have a rash.

“Normally, if people have documented receiving two doses of measles vaccine we would be confident they won’t contract measles, but that’s getting greyer – this research has demonstrated some vaccinated people are getting measles,” Dr Gibney said.

“We do have a definitive test for measles. Our message to doctors is that if you suspect measles, don’t just rely on the serology, which detects antibodies to measles, but also perform a PCR test, which detects the actual virus.”