Updated
There is renewed controversy surrounding influenza vaccines, with some studies showing people immunised against the seasonal flu might have been at greater risk during the swine flu outbreak.
Infectious diseases expert Professor Peter Collignon has called for a review of Australia's flu vaccine policy in light of the new research, but the Federal Government has defended its vaccination program.
Immunisation can be a sensitive issue, particularly when it comes to adverse effects in children.
Professor Collignon from the Australian National University (ANU) says the new research will only heighten sensitivities.
"What was a bit surprising when we looked at some of the data from Canada and Hong Kong in the last year is that people who have been vaccinated in 2008 with the seasonal or ordinary vaccine seemed to have twice the risk of getting swine flu compared to the people who hadn't received that vaccine," he said.
ANU microbiologists say it is the opposite of what vaccines should do.
Professor Collignon says the findings of the study also highlight the benefits for healthy people who are exposed to some illnesses.
"Some interesting data has become available which suggests that if you get immunised with the seasonal vaccine, you get less broad protection than if you get a natural infection," he said.
"It is particularly relevant for children because it is a condition they call original antigenic sin, which basically means if you get infected with a natural virus, that gives you not only protection against that virus but similar viruses or even in fact quite different flu viruses in the next year.
"We may be perversely setting ourselves up that if something really new and nasty comes along, that people who have been vaccinated may in fact be more susceptible compared to getting this natural infection."
The Government's National Immunisation Program (NIP) targets those most likely to have a poor outcome from flu, with the seasonal flu vaccine recommended for anyone over six months old.
Professor Collignon says that in light of the study, the Australian Government and health policy makers need to look at whether vaccines actually do more harm than good, particularly in people who otherwise have not got risk factors.
But the Federal Government's chief health officer, Professor Jim Bishop, says the evidence is patchy.
"There's a study from Canada which might suggest in that direction but there are other studies which contradict it as well, so I don't think that the evidence is clear about the effect of prior vaccine," he said.
Professor Bishop says the Commonwealth's flu vaccination program has been effective and beneficial.
He said IUC admissions were cut from 700 during the first outbreak of swine flu down to about 60 admissions last winter as a result of the vaccination program.
"Secondly, the number of admissions were about one-tenth of what they were the previous year, so that was in the face of a new strain, a new type of virus," he said.
While Mr Bishop says there is no evidence having the flu vaccine is a bad thing, Professor Collignon blames influential drug companies and frightened politicians for what he says is the overuse of flu vaccines in healthy people.
The World Today requested an interview with Health Minister Nicola Roxon, but she was unavailable.