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A version of the H1N1 vaccine intended for pregnant women is now also being offered to healthy adolescents, teens and adults in yet another fundamental shift to Canada’s vaccination strategy.

Federal health officials said yesterday that an adjuvant-free vaccine is not only safe for pregnant women, but also induces a strong immune response in healthy people between the ages of 10 and 64. Provinces and territories, which have received some of the unadjuvanted doses from GlaxoSmithKline’s Ste-Foy, Que., plant, will start offering the vaccine now that Health Canada has authorized its use.

But the latest change in vaccine delivery adds to the confusion and suggests to some experts that the national strategy has become more of a day-to-day improvisation to get needles into people’s arms.

Take the vaccine dosage for children. It was thought that children should get two half-doses of the vaccine, but the Public Health Agency of Canada revised its recommendation this week and said that healthy kids between 3 and 9 only need a single half-dose.

Now there’s the change in who gets the unadjuvanted vaccine: The 1.8 million doses were ordered in September for pregnant women and children under 3, because experts said there was a lack of data around the use of immune-boosting adjuvants in these groups. But then health officials said children are better protected with the adjuvanted version, which contains an immune-boosting additive, and it’s healthy adults who would benefit more from the unadjuvanted version.

“This kind of communication may be the new normal. I think human behaviour is starting to mirror that of influenza virus: changeable, unpredictable and subject to frequent mutation,” said Ross Upshur, director of the University of Toronto’s Joint Centre for Bioethics and a primary-care physician.

David Butler-Jones, Canada’s chief public health officer, said decisions are being made as health officials receive more clinical trial data.

He said Canada bought 200,000 doses of unadjuvanted vaccine from Australia when the GSK plant was unable to produce its version quickly enough. That means there’s enough unadjuvanted vaccine for expectant mothers as well as other groups.

“We find that in adults or those over age 10 with good immune systems, that they in fact mount a very good response. So why wouldn’t we immunize people using that to broaden the number of people that are protected?” Dr. Butler-Jones said yesterday.

The adjuvant-free version is not recommended for people with chronic conditions, young children or those over 65.

The latest changes come as provinces expand their immunization campaigns to include more groups at higher risk of developing complications from H1N1. In Ontario, children under 13 and adults over 65 with underlying health problems will be able to get the H1N1 flu shot beginning next week.

And Saturday Alberta will begin vaccinating people between 18 and 44 with chronic conditions,caregivers of infants under six months old and caregivers of those with suppressed immune systems who cannot be immunized.

Martin Lavoie, Alberta’s deputy chief medical officer of health, said it’s too soon to tell when the province will be able to immunize the general population. But as more groups not considered high-risk are added, the province will re-evaluate how it can use the unadjuvanted supply more broadly.

“We can certainly expand a little bit more. It’s good news,” Dr. Lavoie said.

With reports from Dawn Walton in Calgary and Karen Howlett in Toronto

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