A youngster registers for a swine flu clinic at the Stampede Grandstand in Calgary on Wednesday. (CBC)

Alberta is expanding its swine flu immunization program on Friday to all children under 18, their immediate family members and caregivers living with them.

The stability of the supply of the vaccine, which targets the H1N1 influenza A virus that causes swine flu, has allowed the province to expand eligibility groups this week.

"We expect to be able to open it up more broadly to the general public at some point next week," Dr. André Corriveau, Alberta's chief medical officer of health, said Wednesday.

By Friday, Alberta will have about half a million doses of the vaccine on hand, and will be receiving regular shipments through December, said a news release from Alberta Health Services on Wednesday.

Arrangements are being made "over the coming weeks" to offer the vaccine through family doctors, pharmacies and large employers who have experience with immunization programs.

"If somebody's healthy and not at high risk and can wait a couple of weeks to get it through their employer, that's an option we'd like to be able to provide," said Corriveau.

He could not guarantee that lineups would not stretch into hours, which plagued the first week of the immunization campaign, but pointed out that 600,000 Albertans have already been inoculated which may ease the pressure.

3 more deaths from H1N1

Seniors who were 65 and older as of Nov. 1, and their spouses or partners of any age, will also be able to get their swine flu shot beginning on Thursday.

They join groups already eligible for the shot:

• All children over six months and under five years as of Nov. 1.
• Pregnant women.
• People with chronic conditions aged five to 64 as of Nov. 1.
• Household contacts and caregivers of people who cannot be immunized such as infants under six months and people with suppressed immune systems.
• First responders including firefighters, police and provincial peace officers.
• Seniors over 75 years of age, as of Nov. 1, as well as their spouse or partner.
• Front-line health-care workers.

Proof of age, such as ID, and documented proof of eligibility, such as a prescription, are required.

H1N1 is blamed for the deaths of 43 Albertans since April. The latest three deaths were of women over 50 who all had chronic underlying medical conditions, said Corriveau. Two were from the Calgary area, and one was from Edmonton.

2nd wave waning

Corriveau said while flu cases in intensive care units in Alberta hospitals remain steady, health officials have noticed that the spread of H1N1 in the community slowing.

"This is what we expect between wave two and wave three, things will decrease in the next several weeks, but it won't go away," said Corriveau. "The virus will bide its time. There will be a wave three."

He explained that health officials have not scheduled vaccinations for students in schools because of logistical issues, such as collecting consent forms, training staff and sorting the vaccine into smaller lots.

"We're not ruling out going to schools at some point in the future," Corriveau added.