The H1N1 flu shot prevented nearly one million cases of influenza and 50 deaths in Ontario alone, according to a new analysis that researchers say shows the controversial mass immunization campaign was worth the cost.
Overall, the researchers estimate that the vaccine prevented 420 hospitalizations, 28,000 visits to hospital emergency departments and 100,000 visits to doctor's offices in Ontario, the country's most populous province.
"Ontario's program started just before the outbreak peak," Beate Sander, a University of Toronto doctoral student and health economist, said in a news statement Monday.
"A substantial portion of the population had already been infected at that time. Nevertheless, Ontario implemented the program in time to accrue significant health benefits at reasonable cost but a further delay would have eroded the program's cost-effectiveness considerably."
As of March 6, 25 million doses of the H1N1 vaccine had been distributed nationwide.
The study is believed to be the first to look at the cost-effectiveness of the mass H1N1 immunization program, the largest vaccination program in Canada's history.
Ontario began inoculating people in the highest risk groups on Oct. 26, 2009, two weeks before the peak of the pandemic. By mid-November, the vaccine was made available to every resident. The program cost $180 million.
"When the program was rolled out, there was so much negative press about how expensive it is, what a waste of money it is," Sander said in an interview. "We wanted to look at it in a more formal way."
The researchers knew from Ontario data how many people were hospitalized, how many people died and how many ended up in an intensive-care unit. From that, they created a computer model to simulate what would have happened without a vaccine.
"The vaccine was implemented quite late — almost half of people had been sick by the time it started and it takes about two weeks for the vaccine to take effect. Even then we could save enough patients to make it worthwhile," Sander said.
"Even if you reduce the attack rate — the number of symptomatic cases you have — by two per cent, that's still a lot of people. Two per cent of 12 million is still a lot of people."
Sander said it is difficult to predict what impact the vaccine had nationally.
"So much depends on what point in time the immunization programs started in relation to how the pandemic unfolded — so whether you were before the peak or after the peak, and if before, how much before? And how many people you can vaccinate in a certain amount of time?
"But in principle, vaccination programs almost all have been highly cost-effective. And it's not an expensive vaccine."
The study is published in this month's edition of the journal Vaccine.
Copyright (c) CW Media Inc.