The strains of influenza spreading across Canada are especially harsh this year, while the vaccine is not as effective as would be hoped.

The predominant strain is H3N2 which mutates rapidly and often results in vaccines being less effective.

In Quebec last year the vaccine was only 37 per cent effective against the strain of H3N2 that was infecting people.

This year, Quebec’s public health officials are gearing up to fight the flu, but they aren’t exactly sure what they’ll be fighting.

“What we see already is that we have influenza B around, which is unusual. Usually influenza B starts later in the season and we have H3N2 here in Quebec. In Western Canada, there's still H1N1, so the epidemic that will happen this season is still undecided,” said medical epidemiologist Gaston de Serres.

This year in Australia the vaccine was only immunizing 10 per cent of people, instead of the customary 40 to 50 per cent, and nearly 300 people have died.

"I think when it comes to the high risk patients it's still better than nothing, but I think we have to temper our expectations about what will work," said Dr. Neil Rau, an infectious disease specialist.

"There's nothing wrong in getting it but its benefits are going to be very modest."

Being vaccinated can reduce the extent of symptoms even if it does not provide full immunity.

De Serres said vulnerable groups such as the elderly, children and people with chronic conditions should still get the shot.

“The mortality and hospitalization rate is highest among people over the age of 75, so if you have symptoms of respiratory infections, we recommend you don't visit people in these age groups, because they can acquire the virus and for them, the risk of infections, meaning hospitalizations, and death is much higher,” he said.

In Canada, five deaths around Calgary are being blamed on the flu, while the disease has also hit southern Ontario very hard.

Flu season is expected to peak around Christmas. Officials advise infected people to avoid ERs, saying before they make the trip, call a family doctor or Info-Sante at 811 – saying it will save a lot of time and prevent further spread of the virus.