This year, more than ever, health experts will plead for every Canadian to get a flu shot. The new urgency stems from the similarities between SARS and the flu. Knowing the difference between the two may not only save lives, but help a health care system already under stress.

The new flu season will begin in earnest in a matter of weeks. It's around that time public health officials normally make their plea for people to be vaccinated against what is a preventable illness. But this year there is a new concern -- severe acute respiratory syndrome.

There is little difference between the early symptoms of SARS and the flu and that has health officials worried they may not be able to tell who has which disease.

The situation is especially worrying since doctors fear SARS could return this fall. In total, SARS killed 44 people in Canada this year and infected at least 375 people.

"If we could remove completely influenza from the equation, then there would be much less anxiety over the winter that SARS was coming back," said Dr. Allison McGeer of Toronto's Mount Sinai Hospital.

So, public health groups are urging more Canadians to get a flu shot this fall.

"I think everybody should get it. My feeling about this is that it is a good vaccine that is very worthwhile and has a good effect," said Dr. Ian Gemmill of the Canadian Public Health Association.

Even the World Health Organization has urged people to consider getting vaccinated in light of SARS.

Seniors and the ill are top priorities. So too are health care workers. In Canada, some doctors are recommending children as young as six months old should get a shot.

McGeer told CTV News the flu innoculation has additional benefits for children.

"Influenza is an underappreciated but very common cause of ear infections in kids and for kids getting their flu shot -- it substantially reduces their risk they'll have an ear infection," McGeer said.

This winter, Canadian hospitals will be keeping a close eye on possible SARS cases. New guidelines to be released next week will likely suggest patients showing up in emergency rooms with respiratory illnesses be isolated and tested to rule out SARS.

If more Canadians get inoculated against the flu, experts hope it will ease the pressure on hospitals dealing with potential SARS cases.

"We'd spend less money on lab testing. We'd spend less money on isolation ... It'd be nicer for everybody," McGeer said.

Advocates of natural medicine don't buy the message. They say the flu and SARS can be fought off with good food and exercise and that synthetic vaccines are unnecessary.

"Vaccines are not necessarily the answer. The answer is to work with your immunity on a general or broad sense to prevent against any infectious agents from coming in your body in the first place," homeopathic specialist Bryce Wylde told CTV News.

With a report from CTV's Avis Favaro