As Alberta deals with a spike in flu cases, infectious diseases specialists are warning residents in other parts of the country to get vaccinated before influenza season ramps up in their area.

Five people have now died from the flu, three in Edmonton and two in Calgary, health officials say. There have also been there 965 lab-confirmed cases of H1N1 flu in Alberta; 270 of those patients have had to be hospitalized

Health experts note that lab-confirmed cases don’t offer a complete picture of the outbreak, since the vast majority of those who come down with the flu treat themselves at home, rather than seek testing and treatment in hospital.

Infectious diseases expert Dr. Alison McGeer says the amount of flu activity in Alberta this year is actually not that much higher than previous years.

“In truth, it’s a pretty average influenza season,” she told CTV’s Canada AM Thursday.

But what makes this year different is that H1N1 is the dominant circulating strain. That means that younger people and children are being infected more often compared to other flu seasons, in which seniors tend to be the most likely to become ill.

“H1N1 infections are mostly in children. So it’s not surprising then that the hospital outbreaks in Alberta have been in children’s hospitals,” she said.

On Tuesday, a ward at the Stollery Children’s Hospital in Edmonton stopped accepting new patients because of three lab-confirmed flu cases. Officials say its standard procedure to take such measures when there are more than two confirmed flu cases.

In response to the surge in flu cases, the province opened two new free vaccination clinics in Calgary and Slave Lake on Thursday. On Friday, two more will open in Edmonton and Grande Prairie.

Infectious diseases specialist Dr. Neil Rau says because H1N1 has only popped up as a “sleeper” strain since it was last dominant during the 2009-2010 flu season, it could be that fewer people are immune to it.

Residents of other provinces should take note of what’s happening in Alberta, he says, and get vaccinated before flu season hits their area. And because the vaccine takes two weeks to start having a protective effect, he says, time is of the essence.

“Once the peak of the flu activity or flu wave has ended after four to six weeks in a given area, the benefit of the vaccination is not the same. It has diminishing returns,” Rau told CTV News Channel.

“It may protect against other strains that may show up, but in terms of the H1N1 threat I think the biggest concern is to try to get the right people out for the vaccine before the waves hit in other parts of the country.”

Spreading across Canada

McGeer says Ontario’s flu season started about a week after Alberta’s and infection numbers are now ramping up in B.C. and the Prairie provinces as well. While flu activity in the Maritimes is still low, it’s just a matter of time before it kicks in there too, McGeer says.

In Alberta, Health Minister Fred Horne noted that the flu can be dangerous and that more than 150 flu patients have been hospitalized already this year.

The rate of flu immunization among the general public -- and among health care workers in particular – is a matter of concern, Horne says.

“To date, we have administered in Alberta about 840,000 doses of the vaccine. That’s in a population of about 4 million. So the rate of immunization is not what it needs to be to protect us,” he said from Edmonton.

“And of course, the flu season will not peak until February.”