A Nobel Prize-winning scientist has issued a warning to Australian parents who are reluctant to vaccinate their children.
Professor Rolf Zinkernage said that old diseases could re-emerge without vaccination programs, possibly with worse effects than when they were originally widespread.
He said immunisations may work on a cycle of low-level reinfection rather than immune memory.
“One of the polio vaccines was actually an attenuated replicating live vaccine,” he told The World Today.
“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.”
Professor Zinkernagel won the Nobel Prize for medicine with Australian scientist Peter Doherty in 1996 for research identifying how the immune system recognises virus-infected cells.
He said current vaccination programs should be boosted, because people who were vaccinated 20 or 30 years ago show a drastic decline in their protective level.
“The term ‘immunicological memory’ actually is a nice idea, but doesn’t really explain protective immunity and that has very practical consequences,” he said.
“Because it says if over time they reduce for circulating infections in the population and why do we do that? Because our vaccines aren’t as successful and because hygiene measures have been very successful.”
Professor Zinkernagel said the lack of continued exposure to naturally circulating infections meant a person’s 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.”
He said about one-in-1,000 to one-in-3,000 children with a wild-type measles infection, like the recent small outbreak in Melbourne, would bear “very serious health consequences”.
“A vaccine is not without any potential complications, but potential complications are at the frequency of let us say one in a million,” he said.