Alberta Health Minister Fred Horne says only one in five Albertans and about half of health-care workers have been immunized against influenza so far this year.
He says those rates are too low to adequately protect families and communities.
Health officials in Saskatchewan and British Columbia are pressing the importance of being vaccinated.
Dr. Denise Werker, Saskatchewan's deputy chief medical health officer, said Friday that two children under five and one middle-aged person died in December after contracting the flu.
All had underlying health conditions, so officials can't say that flu was the main cause of their deaths.
The warning is also being sounded in British Columbia by Dr. Paul Van Buynder, Fraser Health's chief medical health officer.
"We are seeing small pockets of very severe disease," said Van Buynder, adding more than a dozen patients on are ventilation because of H1N1.
"We are urging those who have not already had their flu shot to get one. It is not too late."
However, Horne noted that although there has been an increase in flu across Alberta in recent weeks, the numbers are actually similar to last year at this time.
He said the difference now is that many of those affected are younger adults.
There have been 965 lab-confirmed cases, another 251 people have been hospitalized due to influenza and five people have died, Horne said.
- With files from CJME
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