A registered nurse displays a sign as thousands of people wait in line for hours on Thursday to receive their H1N1 flu vaccine at the North York Civic Centre in Toronto. (Nathan Denette/Canadian Press)

Provincial health officials don't yet have final numbers of how many doses of swine flu vaccine they expect to receive next week.

Health ministers are asking Canadians to stay away from immunization clinics this week unless they are in a priority group to receive the H1N1 vaccine.

The number of doses shipped from the manufacturer, pharmaceutical giant GlaxoSmithKline, is down to slightly more than 400,000 this week, from roughly two million doses that were sent in previous weeks.

"I've had conversations with the federal minister and I've asked her to please, and she has assured us that they will, give us … as much advance notice as possible about what the supply is going to be," Ontario Health Minister Deb Matthews told CBC News on Monday.

"We were very surprised on Friday to learn how little vaccine there would be available this week. We need to get more lead time."

Scarce resource

Ontario has been told to expect a much larger shipment next week, but still does not have a final number on how many doses, Matthews said.

"We're a week ahead of schedule getting the vaccine out," Matthews said. "We've got three times as much vaccine on a per capita basis as they do in the United States. We are in relatively good shape, and I hope that this week the clinics will operate much more efficiently."

On Sept. 16, Canada's chief public health officer, Dr. David Butler-Jones, said there would be seven million to 10 million doses of the vaccine available by the third week of October, but that did not happen.

On Monday, Health Minister Leona Aglukkaq said GlaxoSmithKline had overestimated its capacity. Federal and provincial public health officers requested that the company complete production of the seasonal flu vaccine first, since seasonal flu kills on average 4,000 Canadians every year.

Other provinces have responded to this week's shortfall in vaccine availability by delaying or rescheduling mass immunization clinics and limiting shots to high-risk groups.

Clinic changes

On Tuesday, Nova Scotia will offer H1N1 vaccine only to pregnant women and women who recently gave birth, children between the ages of six months and five years, health-care workers and members of First Nations communities, while turning away people with chronic illnesses who are also at high risk.

Ontario's Health Ministry announced Monday that it will be setting up evaluation clinics across the province where people with flu-like symptoms who are concerned they might have contracted the H1N1 virus can go to find out whether they need additional medical attention, instead of turning to emergency rooms or doctor's offices.

Health officials in B.C. opened more H1N1 vaccination clinics across the province on Monday. B.C. also expanded its eligibility list to include children under five, health care workers and those who take care of infants.

On Friday, the Public Health Agency of Canada released a table outlining how many doses of the H1N1 vaccine had been shipped to provinces and territories since Oct. 12, and how many doses of adjuvant and non-adjuvant shots it anticipated being sent this week.

The deaths in Ontario last week of a 13-year-old boy and a 10-year-old girl with swine flu likely pushed people toward getting the vaccine, said Kumanan Wilson, a doctor of internal medicine at the Ottawa Hospital and Canada research chair in public health policy at the University of Ottawa.

There shouldn't be a shortage of the vaccine in the long run, but the perception that it's a scarce resource could be fuelling demand, he said.

A suspected or actual adverse event from the vaccine could quickly push people in the opposite direction. How people perceive the epidemic and the number and severity of cases would also make a difference in demand for the vaccine.

School campaign?

Wilson agreed that focusing on high-risk groups first for the vaccine is a good idea, particularly during a shortage. Mathematical models suggest it's wise to immunize school-aged children to reduce the spread of infections before vaccinating all Canadians who want to be.

"I think it's reasonable that the first group has to be the high risk group," Wilson said.

"But then I think before going to the general population or the next group, they should target the group that's most likely to spread the virus, that would be the school-aged children. And then they can move to the general population."

For the majority of schoolchildren, school-based clinics would likely prove efficient, agreed psychology Prof. Louise Lemyre, who studies psychosocial aspects of health at the University of Ottawa.

"However, vaccination requires parental consent, and this requires significant logistics too," Lemyre said in a email.

Lemyre suggested vaccinating higher-risk youth with pre-conditions now, as well as toddlers who need a parent or caretaker to be present when the vaccine is given.

Unlike in some provinces, where the H1N1 influenza vaccine was first given only to priority groups, the northern territories have been offering the vaccine to everyone who wants it.

While some provinces are grappling with vaccine shortages, Nunavut health officials say they do not expect a shortage in the territory.