The flu season in Canada has started earlier in 2018 than in recent years, with younger people and children seemingly more susceptible to the viral illness, according to the latest public health data.

The number of regions reporting influenza activity across the country continued to increase in the week ending Nov. 17, the latest period for which flu data is available.

According to the latest FluWatch report from the Public Health Agency of Canada (PHAC), the number of flu-related pediatric hospitalizations is “significantly higher than in recent years.”

So far this season, 108 patients with influenza who are 16 or younger have been hospitalized. In the most recent week of monitoring, there were 39 reported pediatric hospitalizations -- “levels not normally seen until late December,” according to the report.

The majority of those cases involved patients between six months and nine years of age, and H1N1 seems to be the predominant flu strain affecting children and younger people.

To date, there have been more than 2,000 lab-confirmed flu cases in Canada, and 98 per cent of them have been influenza A, of which H1N1 was the most commonly detected subtype, according to PHAC.

A quarter of all lab-confirmed flu cases were in adults between the ages of 20 and 44, and 20 per cent of cases were confirmed in those between the ages of five and 19.

Dr. Michelle Murti, a physician with Public Health Ontario, said H1N1 affects younger age groups more because older people have had more exposure to viruses similar to H1N1 and therefore developed better immunity.

In previous flu seasons, when the H3N2 virus was dominant, older people were hit harder, Murti told in a telephone interview from Toronto.

Based on influenza activity reported so far, Murti said H1N1 will likely be the dominant virus throughout the flu season.

For those who have not received a flu shot yet, it’s never too late in the season to do so, Murti said.

“Now is a great time to be getting it…especially with the holiday season, as more people will be spending time together,” she said.

This year’s flu vaccine is expected to be more effective than last season’s, which was not entirely effective against A-H3N2 strain.

While the flu shot is recommended for everyone, the vaccine is especially important for children, seniors and those who spend time with people who are at risk of developing serious complications from the flu, Murti said.

The flu shot is available to everyone older than six months, including pregnant women. A high-dose shot, which provides more protection than the regular vaccine, is available to seniors, who are more likely to have compromised immune systems.

The flu shot takes about two weeks to fully take effect and provide protection against the virus, Murti said.