As Australia continues to navigate its influenza season, experts are warning about a surge in pediatric hospital visits caused by severe flu symptoms among children, signalling a cautionary forecast for Canada in the months ahead.
Since the flu season started in the southern hemisphere in late April, children have made up almost 75 per cent of those admitted to hospital, according to Australian health data.
“There’s a red flag waving at us right now, saying to be on the alert and to get protected,” said Dr. John Yaremko, a Montreal-based pediatrician.
So far, Australia’s flu season is not as bad as it was last year in terms of the number of cases, but what concerns Yaremko is the age group that is most affected.
Although the flu season typically tends to impact the most vulnerable people, such as infants, seniors, those who are immune-compromised or pregnant people, Yaremko said a “high proportion” of children being hospitalized are in the five to 10 age group.
Australian health data shows that since the flu season began, children aged five to nine have been the most impacted by the flu, followed by those under the age of five.
“There’s no question that the pediatric population has been affected,” Yaremko said. “And usually, influenza tends to be worse for kids under five, especially kids under two. And what they’ve seen this year is that the five- to 10-year-olds get quite sick and then are hospitalized.”
He said this is unusual as kids between five and 10 tend to “be healthy” and not have any underlying health conditions. Young children, particularly those under five, are the group most likely to be hospitalized with flu, he added.
“And the reason for this, we don’t know, it’s not clear,” he said. “And that’s what we should be worried about in Canada.”
Low vaccination rates, flu strain
The reasons behind the increased hospitalization of children in this age group compared with others are not yet fully understood, but there are theories among experts. And one is related to the low flu vaccination rate in Australia.
According to the country’s national immunization data system, in 2020 42 per cent of children aged from six months to under five years were vaccinated at this time, compared with 24 per cent now.
And for children aged five to 15, just over a quarter (26 per cent) were vaccinated at this time in 2020, compared with 14.3 per cent now.
“It seems that the vaccination rate in children has dropped considerably this year compared to previous years, and that’s probably the bigger factor that’s leading to hospitalizations rather than a particularly virulent strain or a more transmissible strain,” explained Barry Power, editor-in-chief of the Canadian Pharmacists Association.
Since COVID-19, he said many people have “vaccine fatigue,” which may explain the low immunization rates, however, he stressed the importance of getting the yearly flu shot.
In Canada, the rate of flu shots increased from 39 per cent in 2021-22 to 43 per cent in 2022-23 and is now back to the pre-pandemic level, according to data from Health Canada.
However, the numbers provided only presented data for individuals aged 18 and above, and not for children.
“The vaccine doesn’t always prevent someone from getting the flu, but it can prevent them from getting really sick. And the bigger thing that it can do is prevent people from transmitting the flu,” Power said.
Another possible explanation for the disproportionate impact of the flu season on children compared with adults is the specific strain that is currently circulating, explained Gerald Evans, an infectious disease expert at Queen’s University.
Since the flu season kicked off in Australia, the country has reported that influenza A made up for 65 per cent of cases and influenza B accounted for 32 per cent of cases.
“What’s interesting about this year is they’re seeing a lot more influenza B,” Evans said. “They’re still seeing mostly influenza A, but the number of influenza B is much higher than it was last year. Last year was almost a completely dominant influenza A.”
And influenza B tends to cause more severe illness in children, he added.
What this means for Canada
Australia’s flu season, which typically runs from June to October, has long been looked at by Canadian health experts in preparation for flu season here, which usually begins anywhere between late October and early January.
In an email to Global News, a spokesperson from the Public Health Agency of Canada (PHAC) said officials are monitoring Australia’s flu season for situational awareness.
“Influenza activity in Australia appears to have stabilized after an increasing trend, with nearly all indicators now within historical averages for this time of year,” the spokesperson said, adding that reports showing that children in Australia have been disproportionately affected this flu season likely reflect a lack of natural immunity in this population.
Because Australia’s flu season seems to disproportionately be impacting children, Yaremko recommends getting your child vaccinated against the flu when the shot is made available in Canada.
“If you look at what is happening in Australia, it could easily happen here,” he said.
“I’ll be much more proactive in this age group than I have been in the past and continuing to encourage the high-risk and continue to encourage everybody because it’s such an easy thing to do and it’s a safe thing to do.”
Last flu season, Canada had a scarcity of pediatric acetaminophen and ibuprofen due to the resurgence of respiratory illnesses like the respiratory syncytial virus (RSV), as the pandemic eased and kids started going back to school.
But Power believes the flu season in 2022 and early 2023 was an “unusual situation.” The combination of respiratory viruses with manufacturing delays created a shortage of pain medications.
“Health Canada has worked very closely with the manufacturers of the child and infant products for pain and fever to increase the supply and also to put some measures in place that will help to prevent this from happening again,” he said.
So far, he said pharmacies across Canada have not reported a shortage of medications, as supply has “significantly” increased.
“Some of that is outside the consumer’s hands, but the consumers can do a couple of things. They can get vaccinated. They can get their children vaccinated and then practise all of the respiratory hygiene measures that we learned and used so effectively over the pandemic,” Powers said.
— with files from Global News’ Aaron D’Andrea