TORONTO — A new study suggests this year's flu vaccine has offered little or no protection in Canada against becoming sick enough to require medical care.
That's even less protection than was seen in a study done in the United States that was released earlier this month.
The U.S. study suggested that the vaccine lowered a recipient's risk of contracting the flu and getting sick enough to need medical care by 23 per cent.
That's well below the 50 to 70 per cent effectiveness estimate that is often given for flu vaccine.
Lead author Dr. Danuta Skowronski says the problem this year is that nearly all flu infections so far in Canada have been caused by H3N2 flu viruses, and virtually all the viruses spotted in Canada are different from the one in the vaccine.
In the United States, H3N2 is also the main strain causing illness, but about one-third of the viruses there were a match for the H3N2 component of the vaccine.
The Canadian study suggests that people who didn't get a flu shot last year got more protection from this year's vaccine than those who were vaccinated both years running.
The study is in Eurosurveillance, an online journal published by the European Centre for Disease Control.
