One dose of swine flu vaccine appears to be enough for children, a vaccine committee that advises the World Health Organization reported Friday.

The committee, known as SAGE (Strategic Advisory Group of Experts on Immunization) said a single dose of vaccine is enough to immunize children over 10. It added that while more data on children between 6 months and 10 years are needed, countries should start by giving younger kids at least one dose.

"The SAGE recommendation (for children under 10) could change as more data come in," said WHO vaccine chief Marie-Paule Kieny.

For the time being, she said, "the priority should be to give them at least one dose of vaccine now, and to cover as many of them as possible."

Currently, Canada and many other countries are recommending children under 10 receive two doses of H1N1 vaccine, given at least 21 days apart. That could soon change.

Canada's Chief Medical Officer of Health, Dr. David Butler-Jones, said Friday that experts advising the Public Health Agency of Canada are considering moving to a one-dose recommendation for children, and have been studying the issue for a while.

SAGE also reversed its earlier recommendation that countries offer adjuvant-free vaccine to pregnant women because of a paucity of research on the adjuvanted vaccine in pregnant women.

The committee said animal studies of adjuvanted and non-adjuvanted vaccines found "no evidence of direct or indirect harmful effects on fertility, pregnancy, development of the embryo or fetus, birthing, or post-natal development."

Nor did studies using live-virus flu vaccines, which are not used in Canada; flu vaccines here use inactivated -- i.e. dead -- viruses.

Based on the data review and the fact that pregnant women face an elevated risk of complications from swine flu, the panel recommended that any H1N1 vaccine could be given to pregnant women.

"This is based on the fact that the safety profiles of adjuvanted vaccine and the non-adjuvanted vaccine are very similar and the fact that the non-adjuvanted vaccine has been recommended for pregnant women for many, many years," said Dr. Marie-Paule Kieny, director of the WHO's initiative for vaccine research.

"So there is no reason, in SAGE's view, to distinguish between both types of vaccines."

The WHO noted between seven and 10 per cent of all H1N1 patients sick enough to need hospital care have been pregnant women.

Vaccine flow to slow over next 2 weeks

The WHO's change in policy comes as Canadian health officials announce there will be temporary shortages of swine flu vaccine, because the manufacturer is halting production lines to focus on creating unadjuvanted vaccine for pregnant women.

The Public Health Agency of Canada estimates deliveries of regular swine flu vaccine over the next two weeks will be below the two million doses a week that GSK had been producing for the past few weeks.

But the flow of regular swine flu vaccine is expected to pick up shortly afterward. After the temporary shutdown, GSK is expected to return to producing about three million doses a week.

The hope is that with six million doses already gone out across the country, there will be just enough to cover all the people considered high-priority for first access to vaccine. That's estimated at between seven and eight million people.

Nevertheless, some local health units are already considering cancelling some flu shot clinics. Manitoba warned in a news release Thursday evening: "Regional health authorities may have to adjust their clinic schedules, including postponing clinic dates, until there is sufficient vaccine supply.

In New Brunswick, the first province to roll out vaccines, five schools in the Moncton area were shut down Friday after an outbreak of a sickness that may be H1N1.

The schools won't reopen until sometime next week because so many teachers are sick, there aren't enough to supervise the children. An estimated half of all students were already absent.

Three students tested positive for H1N1 in the area and some parents are believed to be keeping their kids at home because of it.

More long waits expected at Friday flu clinics

All of this comes as flu shot clinics across Canada contend with another day of massive lineups. In Toronto, for example, the lineup for one clinic at Metro Hall began before 6 a.m. -- four hours before the clinic was scheduled to open.

Many of them have now been given slips of paper with a time on it, telling them when to return for their vaccination.

On Thursday, two Toronto vaccination clinics that had opened early for high priority groups saw thousands of people turn up. By early afternoon, the clinics were turning away newcomers. Those who made it to the end of the line waited over six and a half hours to get the vaccine into their arms.

While many in line were clearly pregnant or had small children in tow, for others it was not clear whether they fit the category of "high-priority." But nurses said that no one who waited in line would be turned away.

Flu shot clinics across the country saw lineups that snaked around outside clinic buildings, even in regions where rain was falling and cold winds blowing.

In St. Eustache, Que., more than 1,000 people had to be turned away from the hours-long lineup outside the Centre de vaccination. And in Calgary, wait times at clinics were sometimes as long as six hours, leading to frustration amongst many in line.

Despite the change in policy from the WHO on adjuvanted vaccine for pregnant women, it's expected many will still want to wait for the non-adjuvanted vaccine.

While the Public Health Agency of Canada has stated that adjuvanted vaccines are just as safe as unadjuvanted vaccines, many pregnant women are still worried about the adjuvant and have said they would prefer to stick with the non-adjuvant vaccine.

SAGE also noted Friday that giving swine flu and seasonal flu vaccine flu shots is safe, though live-virus vaccines should not be given at the same time.

Around the world, 14 countries are now vaccinating against H1N1.