Flu season has arrived early this year, causing a dramatic spike in the number of influenza cases across the country.

From coast to coast, patients are crowding doctors’ offices and emergency rooms.

Health Canada confirmed that as of mid-December, there were 3,500 confirmed cases of the flu, compared to just 182 the previous year.

Dr. Allison McGeer, head of infection control at Toronto’s Mount Sinai Hospital, said the particular strain of flu that is going around is linked with more severe forms of illness.

“The strain of influenza that’s causing infection is H3N2. And those flus tend to be associated with more illness and more severe illness,” McGeer said.

The spike in cases could be due to increased socializing during the busy holiday season, Dr. Danuta Skowronski of the BC Centre for Disease Control said.

“We do expect influenza spread to be facilitated over the holiday period,” she said.

In Toronto, there have been 449 confirmed flu cases from Sept. 1 to Dec. 29, more than double what health officials are used to seeing. Almost half of those cases were reported over the holidays, from Dec. 23 to Dec. 29.

And in Alberta, nearly 800 flu cases have been reported, more than half in the last two weeks of December.

Doctors say that while it’s not guaranteed, a flu shot offers patients the best protection and it’s not too late to get one.

“It’s never too late to get an influenza vaccine when we’re in respiratory virus season,” Alberta Health’s Dr. Judy MacDonald said.

To protect against the flu, hospitals in London, Ont., will be asking staff and visitors to wear masks or get vaccinated if they are on a ward where there is influenza. The hospitals say it is a matter of patient safety.

Doctors say young children and the elderly are most at risk for the flu. People with serious medical conditions are also at increased risk.

Those who are stricken with the flu are advised to rest, drink lots of fluids and keep away from the office and other public spaces to avoid infecting others.

Thorough hand washing is also recommended.

“The key thing is to make sure you always wash your hands, before you eat especially,” Vancouver pharmacist Anita Fong said.

With a report by CTV Alberta’s Bureau Chief Janet Dirks