Flu activity seems to be surging just in time for the holidays in several parts of the country, health officials said on Thursday as they urged people to take precautions against catching and spreading the illness.
It's not too late to get a flu shot, they suggested, and also said people can protect their friends and loved ones by not attending parties and gatherings if they are sick.
"We have long recognized that the holiday period is a chance for greater social mixing," said Dr. Danuta Skowronski, an influenza expert at the B.C. Centre for Disease Control in Vancouver.
"We sometimes refer to influenza as the original Grinch who stole Christmas because it can transmit more when there are people gathering in large numbers indoors."
Dr. John Spika of the Public Health Agency of Canada said flu activity has got off to an earlier start this season compared with the past few years, with the influenza A virus H3N2 as the predominant strain circulating in Canada.
H3N2 typically causes more severe illness, especially in seniors, said Spika, who heads the agency's centre for immunizations and respiratory infectious diseases.
He said the most recent reports of laboratory-confirmed influenza cases show activity is high in Ontario and Quebec, and is rising in the Prairies and Atlantic Canada.
He said flu activity may have reached a peak in British Columbia, but Skowronski said her centre's data suggest that isn't yet the case.
Flu is notoriously unpredictable, with seasons peaking at different points in different years. Last year's season, for instance, was the latest in decades, with activity only really picking up toward spring.
But this year's surge is the earliest in about a decade.
"We are seeing a lot of influenza in the hospital. And anecdotally, a lot of people that I work with or people who work with them have been calling in sick in the last couple of weeks," said Dr. Michael Gardam, head of infection control at Toronto's University Health Network.
Gardam admitted that the illnesses might not all be flu. There has also been a lot of sickness caused by respiratory syncytial virus or RSV in recent weeks.
"But it definitely is feeling like we're hitting a peak of influenza. Either now or in the next week or so."
Gardam's advice was pretty basic.
"If you are sick, stay away from people. So don't come into work, don't go to that Christmas party if you're really feeling ill, because that's just unfair to everybody else," he said.
He also advised people to wash their hands frequently and get a flu shot if they haven't already. "And beyond that it's really about trying to stay away from sick people."