Measles now infecting vaccinated people, sparking ‘waning immunity’ fears

Victorian patients who previously received the measles vaccine have fallen ill with the highly infectious disease, sparking fears of “waning immunity” in Australia and other countries which have eliminated the virus.

Victorians already vaccinated against measles are contracting the dangerous disease, raising fears the way it spreads may have evolved.

Melbourne scientists are warning countries which have eliminated the measles through vaccines they are likely to face an emerging problem from “waning immunity”.

Thirteen Victorian patients were hospitalised with measles between 2014 and 2017 despite having had either one or two vaccinations which previously made them immune.

Research into the cases by the Department of Health, the Doherty Institute and Royal Melbourne Hospital has raised discussion about the potential for a third vaccination as well as concerns for doctors’ ability to diagnose measles among those thought to be immune.

A patient receives a measles, mumps and rubella vaccine.

Lead researcher Katherine Gibney said Australia’s success against measles meant people no longer came into contact with the infection, robbing immune systems of the boost needed to stay immunised.

“The epidemiology is changing and that’s partly because we have got such great vaccination programs,” Dr Gibney said. “It is certainly something we will see more of and need to be aware of ready to respond to.”

A highly infections disease, measles claimed an estimated 110,000 deaths globally in 2017, with most victims under five.

A previously immune measles patient has transmitted the disease to two babies.

Although measles was declared eliminated from Australia in 2014 — with the nation’s last recorded death from the disease in 1995 — isolated cases continue, usually among people from nations where it remains prevalent.

Between 2008 and 2017 there were 297 cases of measles in Victoria, of which 190 were analysed by the Melbourne team in research published in the Clinical Infectious Diseases journal.

Of 87 cases reported between 2008 and 2013, none had been vaccinated. However, of the 103 measles cases after 2014, 13 patients had been previously immunised.

In one case a previously immune measles patient transmitted the disease to two babies, underlining the danger of waning immunity.

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While the patients did have the telltale rash, they did not have other classic symptoms of fever, cough and runny nose, presenting issues for doctors trying to diagnose the illness.

Dr Gibney said the emergence of waning immunity underlined the importance of having two measles vaccinations, as well as research into a potential third.

“I don’t think we can say that we need three vaccines yet, but I think it is something we need to keep an eye on and think about in the future,” she said. “We did not see this pattern in kids who had their vaccines more recently, they were all people who had 20-plus years (since vaccinations).”

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