The number of people battling the flu is soaring across the country.

According to the Public Health Agency of Canada's latest FluWatch report, the virus is spreading across much of Canada.

"At the national level, influenza activity has crossed the seasonal threshold, indicating the start of an influenza epidemic," the report states. "All surveillance indicators are increasing and most are above expected levels typical of this time of year."

The national test positivity rate alone nearly doubled in a week, jumping from 6.3 per cent to 11.7 per cent, surpassing the five per cent threshold that puts the country in an epidemic. The hardest-hit communities appear to be located within Alberta, Saskatchewan, Ontario and New Brunswick.

Ryan Weichel’s six-year-old daughter, Sunny, is one of them. Just before her birthday, Sunny spent four days in hospital fighting the flu.

"She endured a lot the last couple weeks. The first five hours she just wanted to go home. Very difficult," Weichel told CTV News.

He said Sunny had a relentless fever which led to a trip to the ER, where she tested positive for Influenza A. Dehydrated and needing treatment, she was admitted to pediatric care after a 12-hour wait. She's finally now home and on the mend.

"It was a very scary situation," Weichel said. "It could become worse and worse as time went on, if we weren’t able to manage the fever and manage the hydration situation."

The Weichels are among an increasing number of families dealing with the flu.

Dr. Colin Furness is an infection control epidemiologist and an assistant professor at the University of Toronto's faculty of information.

"Influenza is very unpredictable," Furness told CTV News from Toronto. "Sometimes it comes in like a lion and goes out like a lamb, sometimes the reverse, sometimes neither. That is a big mystery."

Scientists can look to the southern hemisphere for what's to come. Australia also had an early flu season with a high number of infections. But even in typical years, the death toll can be high.

"A typical influenza season isn’t mild," Dr. Alyson Kelvin, a virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan, told CTV News. "We lose about 3,000 people per year in Canada because of influenza."

Seasonal influenza epidemics occur in most years, but in 2020 and 2021, COVID-19 restrictions drastically reduce the spread. During those flu seasons, the test positivity rate didn't even reach one per cent. This season will be different, and right now, kids are the most impacted.

The latest FluWatch report from the week of Oct. 30 to Nov. 5 shows that hospitalizations for those 16 and younger have risen to more than 70, from 40 the week before and seven the week before that. Children between two and four, and between 10 and 16 years old, account for 27 per cent of hospitalizations, while those five to nine made up 24 per cent. Current test positivity rates are now above seasonal averages dating back to 2014.

Pediatric hospitals have meanwhile reported being overcapacity as a result of the latest waves of respiratory illnesses live influenza, RSV and COVID-19. Doctors and hospital administrators also have spoken publicly about a shortage of staff.

"How this intermingles with COVID and other viruses… I don’t have a crystal ball," Kelvin, from the University of Saskatchewan, said, indicating that that’s what she’ll be watching over the next several weeks.

Experts say the flu shot is effective against the influenza strains circulating right now—if people get it.

With files from CTVNews.ca’s Michael Lee