Canadian researchers say that this year’s flu vaccine appears to reduce the risk of catching the dominant flu strain by 72 per cent – much better than last year’s flu shot.
“A vaccine effectiveness of about 70 per cent means that among 10 cases of influenza in unvaccinated people, the number would have been reduced to just three cases if they had been vaccinated,” explained lead researcher Dr. Danuta Skowronski of the B.C. Centre for Disease Control.
“That’s an important reduction in risk, especially for people with underlying medical conditions who face a greater threat of serious complications if infected by influenza.”
The researchers measured the reduction in H1N1 flu cases that were serious enough for people to seek medical attention, to figure out this number, which is in line with what Australia has been reporting for its vaccine this season. They studied H1N1 cases only, as it is by far the dominant strain of flu floating around right now.
“Vaccine effectiveness we’re learning after years now of studying it, it varies from year to year,” Skowronski said. Generally, it’s more effective against H1N1 – which happens to be the dominant flu strain this season – than H3N2, which has been the dominant strain in the last two flu seasons, she said.
Last year, the flu vaccine was less than 20 per cent effective against the dominant strain of H3N2, she said.
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This year’s flu vaccine is about as effective as in previous H1N1 epidemics, like in the 2013-14 season, she said. So a lot depends on exactly what strain of flu virus is floating around in a given year.
This year, the virus also hasn’t changed too far from what researchers originally put in the vaccine, so it provides good protection. “It’s a good match, basically, this year.”
If you haven’t gotten your flu shot yet, you’re cutting it close, Skowronski said, though she believes it could still be helpful. Flu cases in different parts of Canada have either just peaked or are at their peak, but there’s still several weeks of flu season to go.
Influenza B often makes an appearance late in the flu season too, she said, and the vaccine also protects against that.
— With files from The Canadian Press