Number of flu cases continue to climb in Ontario

WATCH: Some areas of Canada are seeing up to 40 per cent more flu cases than last year. The reason? This year’s flu vaccine isn’t as effective at combating the predominant strain. As Vassy Kapelos reports, emergency rooms are overflowing with infected patients.

TORONTO – The number of people coming down with the flu in Ontario continues to climb.

There were 564 newly confirmed cases of the flu in Ontario during the week ending Dec. 20, 2014 – more than double the 252 reported cases the week before and also more than double the 256 reported during the same week in 2013.

Of the 1,135 total reported cases of Influenza A, H3N2 has been the most dominant strain this season and one that’s not effectively nullified by this year’s flu shot.

The shot was developed last year in anticipation for the next season.  But since then, the dominant form of the strain, H3N2, has mutated and no longer matches the vaccine.

And the H3N2 strain is associated with more hospitalizations and severe illnesses compared to other strains, Dr. Doug Sider, the medical director of communicable disease prevention and control for Public Health Ontario said in an interview Tuesday.

“We’ve got lots of experience with H3N2 to know that of the influenza strains that cause illness, it is the one that is most likely to cause more severe illness, complications, hospitalizations, death,” he said. “It’s an H3N2 season so it’s going to be on the bad end of the spectrum.”

Tweet This Click to share quote on Twitter: "We've got lots of experience with H3N2 to know that of the influenza strains that cause illness, it is the one that is most likely to cause more severe illness, complications, hospitalizations, death," he said. "It's an H3N2 season so it's going to be on the bad end of the spectrum."

That’s not to say people shouldn’t be getting their flu shot, he said. The vaccine is still effective against other strains of the flu and is able to assist, at a less than ideal level, in preventing H3N2.

And contrary to some rumours, the flu shot cannot give you the flu.

“The fact is that people get colds at this time of year, and if you happen to have gotten a flu shot, you’re liable to blame that cold on the flu shot,” Global News medical contributor Dr. Samir Gupta said in an email. “But we have randomized controlled trials that compare a flu shot to  a placebo shot and show no difference.”

WATCH: Dr. Samir Gupta debunks some of the most common myths about the flu.

Toronto is midway through one of the worst flu seasons in years, with “widespread” flu activity throughout the city, according to Public Health Toronto.

There were 152 lab-confirmed cases of influenza in Toronto during the week ending Dec. 20, 2014 – almost 40 more than the previous week and more than the 10-year average.  There have been 456 total reported cases of the flu so far this year.

“I would suspect that we’re at the peak in southern Ontario or very close to the peak,” Sider said.

“What we’re hearing from emergency departments, from the Local Health Integration Networks, from our colleagues in the ministry emergency management branch, we’re pretty inundated with influenza at this point in time.”

Tweet This Click to share quote on Twitter: "What we're hearing from emergency departments, from the Local Health Integration Networks, from our colleagues in the ministry emergency management branch, we're pretty inundated with influenza at this point in time."

And more people could be diagnosed as 2015 begins.

A chart which tracks the week-by-week number of confirmed influenza cases builds through December and typically spikes in the New Year.

According to Google Flu Trends, a tool which compares search terms to official flu statistics, Ontario is dealing with one of the worst flu seasons since 2012.

Right now, Google Trends suggests Ontario is dealing with “high” flu activity, while Quebec, Saskatchewan and Manitoba are dealing with “intense” seasons.