After last year’s mild, almost non-existent influenza season, Canadians could be forgiven for almost forgetting about the nasty infection. But this year’s flu season is off to its earliest start in years, and health experts are reminding Canadians that Christmas parties are the perfect place for viruses to spread.

Not only do we spend more time shaking hands, clinking glasses and kissing cheeks at holiday parties, there is almost always at least one guest who’s feeling “a little under the weather.” Taken together, these are pretty much the perfect conditions for a flu virus.

Dr. Colin Lee, acting medical director of communicable disease prevention at Public Health Ontario, says flu activity is already surging in many parts of Canada right now, with particularly high activity in Ontario.

“Many parts of Ontario are experiencing either peak activity or about to experience peak activity during the last week of December,” he tells CTV News Channel.

The Prairie provinces have seen some sporadic outbreaks in the last couple of weeks, as have parts of Quebec. And since flu seasons in Canada typically start in the West and move eastward, the Atlantic provinces are likely to be hit next.

FluWatch, the flu surveillance network of the Public Health Agency of Canada, says 31 new influenza outbreaks have been reported across the country in the last two weeks, including 24 in long-term-care facilities such as nursing homes, and four in hospitals.

The United States is also seeing an early start to its flu season, which usually peaks in mid-February. A full 29 states are reporting flu activity, with high levels of flu in 12 states, the U.S. Centers for Disease Control and Prevention said Friday.

Flu virus patterns are notoriously difficult to predict, so why we saw little activity last years and an early season this year is a mystery. But experts say that just because the flu season has started earlier doesn’t mean that it’s going to be nastier than usual.

Nevertheless, there is some reason for concern. The predominant flu strain in Canada right now is called influenza A virus H3N2, and it’s a strain that typically causes more severe illness, especially in seniors.

For more Canadians, the flu is an unpleasant annoyance. But it’s also a potentially fatal illness. Between 2,000 and 8,000 Canadians die of influenza and its complications every year, according to PHAC. Many of them are seniors, babies or children with chronic conditions, such as diabetes or asthma.

That’s why public health officials continue to stress that the best way to protect yourself is to get the flu shot. Dr. Lee says that even if the flu is peaking or has peaked in your regions, it’s still a good idea to get the vaccine.

“This is the definitely the time to get the shot. It will be valuable not only for this first wave of influenza but potentially for a second wave that may arrive in February or March,” he says, noting that the annual flu season can sometimes run into May.

Just remember, though, that it takes a couple of weeks for the vaccine to build up a person's immune system enough to fight off the virus, so it’s possible to become ill while waiting for that to happen.

How to tell if you have the flu

Dr. Lee says there are a few other ways to avoid the virus.

“The first thing is if you see someone ill, keep your distance, and perhaps tell them that they should be at home,” he says, adding that if you yourself are ill, do others the courtesy of staying at home as well.

“I think washing your hands even more often than usual is important if you’re going to be around a lot of people,” he adds.

And if you have just developed a cough, how do you know if it’s the flu or just a cold?

In general, a cold is a milder illness that is really only bad for a day or two. The flu, on the other hand, brings on intense exhaustion that leaves most patients in bed for the better part of a week -- and sometimes even longer.

The main hallmark symptoms of the flu are a cough and a fever that lasts two to four days.

Vomiting is generally not a symptom, though in some kids, a fever can cause them to vomit.

If you’re an adult with fever and vomiting, you likely don’t have the flu, but gastroenteritis or food poisoning instead.

In Montreal, doctors are issuing a plea they deliver almost every winter season: if you or your children have the flu, don’t go to already crowded emergency rooms.

They note that the flu is fully treatable at home and there’s little that doctors can do for you while the illness runs its course.

There are exceptions though: if a child is less than three months old or has a fever that hasn’t broken in five days, they should be taken to the ER. Also, if a child has severe trouble breathing or has blue lips or hands, is so sleepy that he doesn't respond when you try to get him up, or has a seizure, they too should be taken to the hospital right away.

With files from The Canadian Press