One of the world’s leading authorities in experimental immunology says Australian parents must think rationally about vaccination.

Old diseases can easily re-emerge when parts of Australian society avoid vaccinating their children, Nobel Prize-winning scientist Professor Rolf Zinkernagel says.

Professor Zinkernagel won a Nobel Prize for Medicine and Physiology for a joint project with Australian scientist Peter Doherty in 1996. Their team successfully identified how the immune system recognises virus-infected cells.

One favoured point of scepticism for the anti-vaccine movement is the fact that some vaccines to not provide 100 per cent immunity to a disease.

Given that it is possible to be vaccinated against an illness and still contact it is reason enough for many parents not to bother.

But Professor Zinkernagel says vaccines are population-level medications which often work on a cycle of low-level re-infection rather than complete immunity.

“One of the polio vaccines was actually an attenuated replicating live vaccine... that vaccine circulated the population and maintained [immunity] by so-called reinfecting people at a very low level, [so people] maintained an active immune response that was protective,” he told the ABC.

There has recently been a small outbreak of a ‘wild’ type of measles in Melbourne, which Professor Zinkernagel says could bear “very serious health consequences”.

He believes vaccination programs should be boosted and made to run longer, as figures show those who were vaccinated 20 or 30 years ago have not kept up the regime, leading to a drastic decline in their protective level.

Professor Zinkernagel says most adults do not receive beneficial continued exposure to naturally circulating infections – sometimes in the low-level form of low-level vaccines – which means that their protective level “decreases and sometimes disappears”.

“So we get back to old diseases we haven't seen for quite some time,” he said.

“That means that we should vaccinate people not only during childhood and the first two or three years of life, but continuously every three to five years.”