With a variety of influenza strains circulating Australia, an expert says it's possible to be struck down with the disease twice this season.
It's certainly not common but it's more than possible to be hit with the flu twice this year as a mix of influenza strains circulate the country.
In the grip of the "worst-ever" flu season, Australians have been told that it's still not too late to get their influenza vaccination that offers protection against four strains in one shot.
Notifications data shows numerous strains are currently circulating the country, including three strains of influenza A and influenza B.
This "mix" of influenza has been driving notifications up, with the total number of cases across the country now surpassing 70,000.
With so many of the strains being reported and immune systems down, Professor Robert Booy says it's feasible someone would be "unlucky" enough to be struck down with more than one strain of flu.
"We've seen it in our clinical experience and we have seen it in all sorts of people, including nursing homes," said Prof Booy, who is head of the clinical research team at the National Centre for Immunisation Research and Surveillance (NCIRS).
"The immunity is not just whether you've had flu A because you can get another strain of flu A and you can get another strain of flu B," he told AAP.
Professor Bill Rawlinson, a senior virologist, says the current vaccine covers strains A (H1N1), A (H3N2), the B Brisbane strain and B Phuket strain.
"It's not too late to get vaccinated," Prof Rawlinson said.
Data released by the Immunisation Coalition on Tuesday also showed children aged 10-19 had been hit the hardest by this year's outbreak.
While this is not unusual, one possible explanation is there has been more influenza B circulating, says Prof Booy.
"We've had a lot of B and a lot of A so that may have increased a little bit the amount of childhood disease but we always have a peak in young children and older people," he said.
The expert also said there was no evidence to suggest the strains have been more virulent this year.
"We've got no evidence that it's nastier," Prof Booy said.
"What we do know is that there's always a spectrum and actually the great majority of people suffer from symptoms that feel just like a cold; maybe a third get it severely where they can't get out of bed and they've got a high fever, bad headache and go and see GP. Only a few per cent get sent by the GP through to hospital," he said.
Prof Booy says anyone who develops symptoms should promptly consider seeking antiviral medication, such as Tamiflu, from their GP.
"If you see the GP within 48 hours of developing illness it can work quite well. This is one time of the year when its important for GPs to consider prescribing it, particularly to people they think might need to go to hospital.