OTTAWA - A promised torrent of H1N1 vaccine is suddenly slowing to a dismal trickle just as public demand for the shot surges in the face of escalating concern about swine flu.

With would-be vaccine recipients joining day-long lineups in Toronto and elsewhere in Canada, officials in Ottawa warned Friday that delivery of vaccine to the provinces is poised to slow down dramatically next week.

Slightly more than 400,000 doses of the adjuvanted version of the vaccine, which contains a booster compound, will flow from the Quebec manufacturer GlaxoSmithKline by the end of next week, said Dr. David Butler-Jones, Canada's chief public health officer.

"We have been getting about two million doses a week," Butler-Jones told a news conference. "That's where the six million doses that are currently out there comes from."

Of that six million, some provinces may still have some left. But those supplies will likely be depleted by the end of next week, said Butler-Jones.

Ironically, the delay is partly the result of a change in production lines to allow GlaxoSmithKline to produce more of the unadjuvanted vaccine, which until Friday was considered the preferred option for pregnant women.

On Friday, an expert committee that advises the World Health Organization on vaccine issues reported that pregnant women should feel free to use adjuvanted vaccine, and that a single dose of H1N1 vaccine should be adequate for all age groups, even very young children.

More than 200,000 doses of the unadjuvanted version of the vaccine, which until Friday was considered the preferred option for pregnant women, are also being imported from Australia.

Ontario's health minister has already warned local health units they will receive only a fraction of the doses of H1N1 vaccine they had been expecting. In Toronto in particular, where inoculation of the general public had been scheduled to begin Monday, clinics have been besieged by huge numbers of people and lineups lasting as long as seven hours.

Those who are considered to be at low risk of contracting the H1N1 virus are now being urged to stay away from vaccination clinics until further notice.

"Those who are at a low risk group, you will be able to get vaccine (but) your risk of severe illness and death is very, very small," said Butler-Jones.

"Please make room for others."

In the wake of the expected slowdown in vaccine delivery, some jurisdictions have adjusted their plans:

-- In Prince Edward, plans to vaccinate children for swine flu have been put on hold. It could be mid-week to late next week before the elementary school vaccination process gets underway.

-- In Nova Scotia, health officials have decided to restrict access to swine flu shots next week to only those needing it the most. Dr. Robert Strang, the province's chief public health officer, announced Friday that only those in high-risk groups will be inoculate for the time being.

--In New Brunswick, a shortage of vaccine has forced health officials in New Brunswick to cancel some public clinics and impose new rules limiting the shots to priority groups.

-- In Ontario, the province's top health officer is telling healthy people to stay away from H1N1 clinics for the time being, and to keep the lines open for priority groups, including children under five, pregnant women and people with certain pre-existing health conditions.

-- In Manitoba, Dr. Joel Kettner, the province's medical officer of health, said some mass vaccination clinics may have to be postponed.

-- Calgary's five swine flu vaccination clinics shut their doors around noon Friday because of overwhelming demand. The clinics were to reopen Saturday, but provincial officials warned that some clinics could again be temporarily suspended as supplies from the federal government dry up.

--In British Columbia, a shortage of the H1N1 flu vaccine in Canada means healthy residents will have to wait at least an extra two weeks before getting the shot in a province that's seen the highest rise in cases.

Meanwhile, Quebec has begun demanding identification before doling out H1N1 vaccinations after a chaotic scene at one injection site that was flooded with out-of-towners and low-priority patients.

The appeal comes after health officials were overwhelmed this week at the first vaccination site opened near Montreal, at an old car dealership in the small town of St-Eustache.

And five schools in southwest New Brunswick closed Friday with swine flu as the likely cause. Provincial officials say the schools closed because of a shortage of staff. An official with the province's Education Department says it's likely that at least of some of those who are sick have swine flu.

The H1N1 virus also forced the closure of schools in Vancouver and Conne River, Newfoundland.

After next week, federal health officials expect delivery of vaccines to increase, to roughly one million, and then to nearly 3.5 million weekly.

"So, again, we'll be in good position in terms of offering vaccine to those who wish it before we get to Christmas," said Butler-Jones.

The vaccine shortage means there could be more chaos ahead as health officials struggle to meet surging demand for the swine flu shot, federal Liberal Leader Michael Ignatieff said in Windsor, Ont.

The Conservatives spent $60 million promoting its economic plan with "flagrantly partisan" ads, and only a fraction of that on informing Canadians about the vaccine, he charged.

"There's very substantial confusion and that confusion is directly attributable to the conduct of this government," he said.

"What is more basic for a government to do than to provide good public health information to all citizens? And they've failed."