Cases of seasonal influenza spiked over the holidays with 71 laboratory-confirmed influenza outbreaks, including 49 in long-term care facilities, reported across Canada in the final week of 2016.

New numbers released by Canada’s Public Health agency on Friday show that influenza detections, hospitalizations and outbreaks reached a peak between Dec. 18 and Dec. 31.

The largest number of hospitalizations and deaths reported were among adults older than 65. The second highest group affected were adults aged 45 to 64.

H3N2 is the most common strain circulating in Canada this season, representing 99 per cent of all subtyped influenza A detections. Public Health experts say H3N2 is a tough form of flu, particularly among the elderly.

Health Canada noted a week-to-week rise in positive testing for influenza at the end of 2016, but those numbers appear lower than the final two weeks of the 2014-2015 flu season, which was also dominated by the H3N2 strain.

In total, 1,948 positive influenza detections were reported nationally in the final week of the year, up from 1,229 in the previous week.

The latest Health Canada numbers follow an earlier trend in a Dec. 11-17 report that seniors and the elderly accounted for the largest proportion of flu-related hospitalizations and deaths. Of the 18 laboratory-confirmed flu outbreaks reported in that week, the majority occurred in long-term care facilities.

Karen Quigley-Hobbs, director of infectious diseases in the Region of Waterloo, told CTV Kitchener earlier this week that the area “has seen increased activity since Christmas.”

Health officials are recommending the flu shot to defend against the virus. Quigley-Hobbs is optimistic: Unlike the 2014-15 flu season, during which an H3N2 vaccine proved largely ineffective, this year’s vaccine is a “really good match.”

Ahead of the flu season, provinces and territories bought approximately 11.6 million doses of vaccine at a cost of around $75 million, according to Canada’s Public Health Agency.

With files from CTV Kitchener and The Canadian Press