Influenza is taking a higher-than-usual toll on children in Canada so far this flu season, with the virus sending an above-average number to hospital and killing at least eight, including a boy and girl who attended the same Guelph, Ont., school.
Infectious disease experts say the increased flu level among children is likely due to the early arrival of a strain that can be harder on the young, and there is no reason to believe the 2017-2018 flu season will prove to be worse over all than other non-pandemic seasons in the past decade.
This flu season has been unusual in that the A and B strains of the virus gathered steam and spread at virtually the same time, rather than in separate waves.
Influenza A often dominates through the winter, while influenza B usually peaks in the spring.
"Kids are differentially affected by influenza B," said Theresa Tam, Canada's chief public health officer. "Influenza B can affect the whole range of age groups but results in particularly severe outcomes for kids, particularly the youngest of children."
The two Guelph pupils died of influenza B, the local health unit confirmed on Friday.
Layna Vu Pollard, 12, and Boyqara Dahi, 7, both students at Westminster Woods Public School, died on Jan. 31 and Feb. 8, respectively.
Their deaths, along with the flu-related death of a 10-year-old boy in the nearby town of Waterdown on Feb. 4, sent parents in the area scrambling to vaccinate their children.
"We did see a huge increase in demand for vaccinations," said Nicola Mercer, the medical officer of health for Wellington-Dufferin-Guelph, a region about an hour's drive west of Toronto. "We ran flu clinics on Friday evening, on Saturday and on Sunday. In those three days we did over 1,700 immunizations. We had 12 nurses at one site working as fast as they could."
Part of the reason for a heightened fear of the flu in the area is the sudden and unexpected way the three children died.
Layna, a healthy Grade 7 student who loved to dance, write poetry and make short films with her father, developed run-of-the-mill flu symptoms on Jan. 29.
Two days later, on the morning of Jan. 31, she texted her mother from her bedroom to ask for some soup; 15 minutes later, she collapsed on the bathroom floor.
"When my wife found her in the bathroom, she called me, I came running and started doing CPR and phoned 911," Stan Pollard, Layna's father, told The Globe and Mail. "We tried so hard. Her eyes were staring at me when I was giving her CPR. That's going to stick with me for the rest of my life."
Layna was pronounced dead at Guelph General Hospital soon afterward.
Bobby Smylie, the 10-year-old Waterdown boy who died on Feb. 4, was a healthy athlete who loved soccer and Brazilian jiu-jitsu.
"When I took him up to the hospital on Sunday, I figured we were just going in for some antibiotics," Bobby's father, Rob Smylie, said during a eulogy for his son, posted online. "I didn't know that he was critically sick and he would perish that day."
Mr. Smylie told the Hamilton Spectator that his son died of bacterial pneumonia, a complication of the flu. The public health unit in Hamilton would not reveal what strain he had.
The third child to die, Boyqara, had cerebral palsy, a condition than can make patients more vulnerable to complications from influenza. But his father told a local CTV affiliate he was shocked at how quickly the boy deteriorated and died.
CTV reported that Boyqara did not receive a flu shot this season. Neither did Layna, her father said. It's unknown whether the third child was vaccinated.
A mid-season analysis of the flu shot's effectiveness in Canada found this year's vaccine has been much more effective in preventing infections caused by the B strains of the virus – 55 per cent versus only 17 per cent for the AH3N2 strain that has circulated most widely this season.
"The bottom line is that less than a quarter of the pediatric population actually gets the flu vaccine," Dr. Tam said. "It's not necessarily a matter of low vaccine effectiveness, it's a matter of the fact that people are actually not vaccinated."
Influenza rarely kills children, but there are a handful of such deaths in Canada most years.
The vast majority of influenza deaths occur in people over the age of 65.
The IMPACT network, an immunization-monitoring program that tracks the number of children who are are admitted to hospital or die of influenza at 12 Canadian children's hospitals, has confirmed five flu-related deaths this season as of Feb. 3.
That total does not include the deaths in Guelph and Waterdown, which happened at hospitals outside the IMPACT network.
Five pediatric deaths at IMPACT hospitals is a higher-than-normal total at this point in the flu season: In four of the preceding seven seasons, IMPACT recorded no such deaths by early February.
In the other three seasons in that period, the network logged four or fewer deaths by early February. (The Public Health Agency of Canada, which releases IMPACT's figures, won't provide specific numbers when there are between one and four cases, citing privacy concerns.)
However, IMPACT recorded additional pediatric flu deaths by the end of each of those seasons, with a total of eight in the 2015-2016 season being the most in any season after the H1N1 pandemic hit in 2009-2010.
This season, the number of weekly pediatric flu hospital admissions recorded by the network has been above the seven-year average every week since early November.
The 12 IMPACT sites have recorded 511 hospital admissions because of the flu as of Feb. 3, higher at this point in the season than in any post-H1N1 year except 2012-2013.
Still, Allison McGeer, an infectious disease expert at Sinai Health System in Toronto, predicted the numbers will even out by the end of the season.
"I think what we're seeing at the moment that looks like more disease in children is actually just that the flu A and flu B waves are concurrent this year," Dr. McGeer said. "I don't think that this is going to end up being a year that is worse for children over all than other years."