A deadly strain of flu has killed 94 people in Victorian aged-care facilities so far this year, leading to calls for more frequent vaccination against the virus for those who are most vulnerable.

Case numbers have continued to climb across the country this month, making 2017 one of the worst years for influenza in recent years.

More than 160,000 people have contracted the flu in Australia so far this year, Health Department figures show, compared with 75,818 recorded cases for the same time last year. In Victoria there have been just over 13,000 cases.

A spokesman for the Victorian Health Department said that from January 1 until last Thursday there had been 94 deaths from influenza in the state's aged-care facilities. Last year there were 46 during the same period.

The spokesman confirmed that this was attributed to H3N2, a fast-mutating strain of the flu that is defying medical experts' efforts to stop it.

In Victoria, 70 per cent of people diagnosed with the flu since the beginning of the year have suffered from influenza A H3N2, Australian Sentinel Practices Research Network statistics show.

Overall in Australia, 74 per cent of cases have been influenza A H3N2. Thirty-three per cent have been influenza B, and 4 per cent influenza A H1N1.

ASPREN, a network of general practitioners and primary care providers, collects information on influenza-like illness and other conditions seen in general practice. Their data is used for infectious disease surveillance by health departments at state and federal levels.

"This looks like it's going to be the worst year since the 2009 pandemic, but we can't say to what extent at this stage as the rates have not gone down yet, so we are unsure if we have reached the peak or not," ASPREN program manager Monique Chilver​ said.

"The H3N2 causes severe disease in the elderly and the young, and unfortunately our preliminary vaccine effective estimates look like the vaccine has been quite ineffective in these groups."

Currently people receive their vaccinations in April, months before flu season starts.

Ms Chilver said the research should look at offering the elderly a second vaccination, to prevent the disease from becoming so widespread, particularly in aged-care facilities.

She said offering a booster vaccine for Australians aged over 65, midway through flu season, could help combat the flu's spread.

"We know that the vaccine isn't 100 per cent effective, so it makes sense that by having two doses you're giving a better chance of protection," she said.

In the United States, a stronger and more effective flu vaccine for the elderly, Fluzone​, has been used since 2009.

Fluzone manufacturer Sanofi Pasteur said the company was looking to have the drug approved by Australian regulators. 

Australian Medical Association vice-president Dr Tony Bartone said the flu season had been the worst in at least eight years – but that the worst of the season was likely over. 

"It's been a very severe flu season, one in which we've seen an early spike and a longer spike than normal in a number of cases, especially in the northern states and in South Australia and, to a lesser extent, in central Victoria," Dr Bartone said. 

He said the AMA would await the Chief Medical Officer's influenza report for 2017 – usually released before the end of spring – before backing any calls for further vaccinations.

"We need look at all the advice and assess all the evidence," he said.

- The Age, with Joe Hinchcliffe