TORONTO - New data on who got a flu shot in Canada last year underscores a challenge public health officials may face as they plan for a mass swine flu vaccination campaign: most young adults don't get flu shots.

Just under a third of Canadians aged 12 and older got a flu shot last year, Statistics Canada reported Friday in data drawn from the Canadian Community Health Survey, an annual effort to collect health information on a broad cross section of Canadians.

But that average was drawn upwards by the fact that 67 per cent of people 65 and older were vaccinated against influenza last fall.

The rates were substantially lower among people in their teens, 20s, 30s and 40s -- the group which currently appears to be at highest risk of catching the novel H1N1 flu virus and of having severe disease or dying if infected.

Only 26 per cent of those aged 12 to 64 took the preventive seasonal flu vaccine in 2008, Statistics Canada said.

Among healthy males, about 21 per cent of teens, 15 per cent of those 20 to 34 and 19 per cent of those aged 35 to 49 had a flu shot. Among healthy females, the rates were a bit higher in most age categories: just over 20 per cent of teens, 23 per cent of 20 to 34 year olds and 25 per cent of those aged 35 to 44 got a flu shot.

Flu vaccine is more strongly recommended for people with chronic conditions such as asthma, chronic bronchitis, emphysema, chronic obstructive pulmonary disease, diabetes, heart disease, cancer as well as for stroke survivors.

Among Canadians with at least one chronic health condition, 73.1 per cent of seniors and 38.3 per cent of those aged 12 to 64 received a flu shot last year.

When broken down by age, about 25 per cent of male teens and 32 per cent of female teens with chronic health conditions got a flu shot.

The rates were lower in those aged 20 to 34 with at least one chronic condition -- 20 per cent of males and about 26 per cent of females were vaccinated against flu. In those aged 35 to 44 about 27 per cent of males and 36 per cent of females got a flu shot.

People living in urban areas were slightly more likely than those living in rural areas to have had a flu shot in 2008 -- 32.1 per cent versus 29.8 per cent.

Nova Scotia had the highest flu vaccination rate, with about 40 per cent of people taking a flu shot. Ontario, where flu shots are free to anyone who wants one, followed with a rate of 36.6 per cent.

The report did not give breakdowns for the rest of the provinces or territories, though it did note that Newfoundland and Labrador, Quebec, Manitoba, Alberta and British Columbia were below the national average for flu immunization.

The CCHS is an annual survey of Canadians aged 12 and older living in private households, but excludes members of the regular Armed Forces, residents of native reserves and military bases and some remote areas.

In 2008, the overall response rate was 75.2 per cent in a sample size of 66,013. Interviews were conducted either by telephone or face-to-face.