Flu cases continue to “increase sharply” in Canada, according to the Public Health Agency of Canada, which released new figures Friday that also show a spike in hospitalizations among influenza patients as 2013 came to a close.

The new data, which covers the two-week period between Dec. 15 and 28, indicates that the number of positive influenza tests increased from 382 the previous week (week 50), to 754 between Dec. 15 and 21 (week 51) and to 1,152 in the week of Dec. 22 to 28 (week 52).

The agency says that more than 90 per cent of cases so far this year are Influenza A, with H1N1 being the predominant strain. And while flu typically has a greater impact on vulnerable populations, such as the elderly, a greater number of patients falling ill are adults under the age of 65.

H1N1 was last the dominant flu strain in North America in 2009-2010, and has emerged once again this year. Parts of Alberta have been grappling with a flu outbreak that has killed three people in Edmonton and two in Calgary and sent hundreds to hospital.

The province opened more flu-shot clinics on Thursday and Friday in the hopes of increasing vaccination rates and stemming the spread of the virus.

Canadians urged to get vaccinated

Residents of other provinces should take note of what’s happening in Alberta, he said, and get vaccinated before flu season hits their area. The protective effect only kicks in two weeks after receiving the vaccination.

“Once the peak of the flu activity or flu wave has ended after four to six weeks in a given area, the benefit of the vaccination is not the same. It has diminishing returns,” Rau said.

“It may protect against other strains that may show up, but in terms of the H1N1 threat I think the biggest concern is to try to get the right people out for the vaccine before the waves hit in other parts of the country.”

The PHAC report said that three regions in Ontario reported localized flu activity in week 51. In week 52, four regions in Ontario, one region in Saskatchewan and one in the Northwest Territories reported localized flu activity.

The PHAC data also reported a spike in hospitalizations, particularly among younger patients. The agency reported that the number of “laboratory-confirmed influenza-associated” hospitalizations of patients age 16 and under increased from 14 in week 50 to 37 in week 51 to 50 in week 52. The number of hospitalizations among patients over the age of 16 jumped from 17 in week 50 to 40 in week 51 but decreased to 21 in week 52.

Public Health Agency of Canada: Flu Data