Australian adults born after 1966 may not be fully protected against the measles virus because of historical inconsistencies in how the immunisation vaccine was administered.

As Melbourne and Sydney each grapple with a measles outbreak in which 13 cases have been recorded in the past fortnight, health officials are warning adults between 26 and 52 years of age that they may not be properly vaccinated against the virus.

“The advice is if you’re not sure, it’s better to get an extra dose,” Vicky Sheppeard, the director of communicable diseases at NSW Health, said.

Although measles vaccination programs began rolling out across Australia from the 1960s, the second dosage now viewed as necessary to be fully immune to the virus was not introduced until much later.

Currently children are given two doses in infancy – one at 12 months and another at 18 months.

But the National Centre for Immunisation Research and Surveillance says the second dose was not fully funded until 1992 and was initially administered when students were in high school, meaning coverage of the vaccine was not as comprehensive.

“Very commonly it’s young adults, and particularly people in their late 20s, 30s and even 40s who we see contracting the virus,” Sheppeard said. “That’s because when they were children the immunisation program was still changing.”

Officials say people older than 52 are unlikely to have been vaccinated but would likely have either had the virus as a child or been exposed to it sufficiently to make vaccination unnecessary.

On Tuesday health officials in NSW confirmed two people in Sydney’s north and south had been diagnosed with the virus.

In one of the cases, the person, from Sydney’s northern beaches, had recently visited Melbourne, where 11 cases of the virus have been recorded in a fortnight.

It marks the 70th case of measles in Australia so far in 2017 and has prompted a warning to be aware of symptoms such as fever, sore eyes and a cough followed a few days later by a non-itchy rash.



The World Health Organisation declared that Australia had officially eradicated measles transmission in 2014 and 95% of all Australian five-year-old children are fully vaccinated. But there are still dozens and often hundreds of cases recorded each year.

Since 2000 there have been 1,884 confirmed measles cases in Australia, including a high of 339 in 2014 and a low of nine in 2005.



Sheppeard said the majority of cases recorded in Australia came after travelling overseas to places like Bali or Thailand with poorer immunisation rates.

“In most cases travellers come back and develop the infection but don’t spread it to others,” Sheppeard said. “But sometimes, like now, you see small outbreaks. Earlier this year we had a cluster around Sydney’s CBD [and] in 2010 we had a larger outbreak where one person coming back from Thailand brought back 169 secondary cases that were linked to a hospital waiting room in south-west Sydney.”

But if such a high proportion of Australia’s population is vaccinated, how does the measles virus still spread at all?

Prof Peter Collignon, an infectious diseases expert from the Australian National University, said one issue was with “pockets” of populations with poorer immunisation rates.

“It’s important to identify those areas because while we may have good vaccination rates, if we have pockets of low immunisation then something highly infectious like measles will obviously spread to a lot more people,” he said.

“Immunisation rates are pretty good across Australia but in northern parts of NSW or in suburbs of inner-city Melbourne, for example, there are social or economic groups not getting vaccinated.

“They’re often people who are [financially] better off, perversely.”

Statistics back that up. In June the Australian Institute of Health and Welfare released data that showed that while immunisation rates in children continued to rise, there were still some areas lagging behind.

The data, from 2015-16, found the 2000 postcode, which covers central Sydney, had the lowest rate of full immunisation for five-year-olds, at only 70.5%.

The 2481 postcode, which covers Byron Bay, was the third lowest, with 73.2%.

Sheppeard said the reasons ranged from a “questioning of science”, to some areas with large migrant populations having less access to immunisation.

“In northern NSW, for example, it’s often about people questioning government and generally held beliefs about science,” she said. “In some parts of the east suburbs and lower north shore of Sydney there’s a similar questioning of vaccines.

“Then with areas larger areas with larger migrant populations it’s about learning to understand Australia’s immunisation system; that they’re free and how to access them.”