The Alberta Health Services hopes that Albertans take advantage of reopened immunization clinics in an effort to stem the tide of a serious flu outbreak.

Last week, more than 660 cases of flu were confirmed, with a majority being of the H1N1 strain, which is very concerning for health authorities.

Clinics will be open on Thursday and Friday in major Alberta centres including Calgary, Edmonton, and Slave Lake.

One clinic, open at Brentwood Village Shopping Centre in northwest Calgary, has large lineups of people who have heard the news and are eager to get their shots to protect themselves and their kids.

"On the news, they said there was a higher risk for people my age, so I thought that seeing as though kids are in school and a part of different activities, it's probably best to go on the side of caution and get it done," says mom Heather Penner.

Another man said it was important for his daughter to get the shot this year. "She was quite sick last year, so I just want to avoid it this year."

Andy Anton, a local physician, brought his kids in to be immunized. He's seen a lot of really sick patients at Calgary ERs. "It seems to be hitting a lot of younger people and lots of kids are being affected as well. Not in terms of absolute numbers, but the severity of the people who are getting influenza this year seems to be worse than in recent years."

The clinics will be open in Calgary through all the way to the end of March.

The outbreak has forced the Stollery Children’s Hospital in Edmonton to close one of its units to new patients.

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.

(With files from CTVNews.ca)