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(Bill Braden for The Globe and Mail)
(Bill Braden for The Globe and Mail)

Swine flu vaccine at the ready - awaiting Health Canada's approval Add to ...

Hoards of the H1N1 influenza vaccine are being stockpiled in provincial and territorial warehouses, with the gates ready to swing open when Health Canada gives the green light, which could come as early as Wednesday.

The H1N1 virus, mild for the most part, has not been the global catastrophe some feared. But as the regulatory body approves the vaccine and the country embarks on the largest ever mass vaccination campaign in its history, health officials warn that a second wave is materializing and we're not out of the woods just yet.

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"We're seeing disease now. And we're seeing increasing disease in British Columbia and we're seeing it in Ontario right now," said Donald Low, chief microbiologist at Toronto's Mount Sinai Hospital.

To date, about 4,700 people worldwide have died of H1N1, including 83 deaths in Canada. There have been more than 399,000 laboratory-confirmed cases of H1N1 flu, but many countries, including Canada, have stopped counting individual cases because disease is so widespread.

All this started more than six months ago with the realization that a mysterious new flu bug was spreading through Mexico, quickly extending its reach around the globe, infecting hundreds of thousands, and, here at home, testing Canada's ability to protect itself against a pandemic.

The virus

As Mexican scientists grappled with an ever-worsening outbreak, the first known infections were identified in California. On April 17, the U.S. Centers for Disease Control and Prevention alerted the World Health Organization to two unrelated children diagnosed with swine flu.

By the time health authorities understood its pandemic potential, it was circulating freely through Mexican villages and the United States. The World Health Organization declared swine flu a pandemic in June.

Here in Canada, the virus took its toll on members of northern Manitoba reserves, who made up a disproportionate percentage of the ill. At one point in the spring, two-thirds of all Manitoba flu patients on respirators were aboriginal.

Over the summer, dozens of children at overnight camps in Ontario's Muskoka region were sent home or isolated with symptoms of swine flu.

Health officials braced for a fall resurgence when kids returned to school and classrooms served as incubators. The virus is now widespread in British Columbia and the Northwest Territories, and it is expected to move from west to east.

What is particularly troubling is that H1N1 disproportionately affects younger people, unlike seasonal flu, which burdens the elderly. That's because the virus resembles a strain of flu that circulated before 1957, to which older people have been exposed.

Michael Gardam, director of infectious diseases prevention and control for the Ontario Agency for Health Protection and Promotion, said the virus, although mild for many, shouldn't be dismissed so easily. "This thing will typically take about a year to 18 months to run through its course before this strain becomes the usual seasonal strain," Dr. Gardam said.

The vaccine

There was an immediate problem with the rush to crank out a vaccine: The new virus strain was not growing fast enough in the eggs used as a mainstay of flu vaccine production. Manufacturers reported strains were producing barely half as much yield to make vaccines as the seasonal flu virus.

Canada was in an enviable position. Ottawa ordered 50 million doses of vaccine from GlaxoSmithKline, which has a plant in Ste-Foy, Que. And by ordering an adjuvanted vaccine, which contains chemical boosters that can increase production, more could be produced using less seed stock.

Despite the planning, it has been a bumpy road.

First, a controversial unpublished study threw vaccination strategies into disarray. The study suggested that people under 50 are twice as likely to contract the H1N1 virus if they have received a seasonal flu shot. Most provinces and territories shifted their seasonal flu strategies, offering it this month only to the elderly, who are at low risk of catching H1N1, and residents of long-term care facilities. After that, the swine flu vaccine would be rolled out when it becomes available and then seasonal flu shots resumed in December or January.

Adding to the confusion, Ottawa kept shifting its timeline for the vaccine's rollout. Now, it appears that the regulatory body could approve it today, which means that places like the Northwest Territories will begin inoculating their populations as early as next week.

One piece of the puzzle is still missing: The federal government ordered a small amount of non-adjuvanted vaccine for pregnant women and young children because there was no clinical data about the effects of the adjuvant on expectant mothers. It remains unclear when this vaccine will be ready, and there are mixed messages from public health authorities around whether pregnant women should wait for the non-adjuvanted vaccine.

Dr. Gardam said that while Canada has ordered more than enough doses and has a good pandemic plan, its communication on the vaccine rollout needs improvement. "I think the issue surrounding the vaccine has been particularly challenging, where even today I'm reading conflicting news reports," he said.

Follow on Twitter: @calphonso

 

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