It turns out this year's flu shot is only preventing less than 20 percent of infections caused by the dominant strain sweeping the country.
The same vaccine was used last season and was much more effective, suggesting the virus has genetically mutated.
But a researcher at the BC Centre for Disease Control says the flu shot is 55 percent effective overall in preventing cases of the respiratory illness caused by the dominant B strain of influenza, which is also affecting Canadians this season.