To a lesser extent, adults’ resistance to the flu is also lower than it otherwise would be because fewer people received the immune boost of a recent winter infection, says infectious disease expert Dr. Susy Hota, emphasizing the added importance of flu shots this season. “Our immune responses are enhanced to some extent when we see these viruses more often,” said Hota, medical director of infection prevention and control at the University Health Network. “We haven’t really had that in the last couple of years. So people could become more symptomatic and get these infections and notice them more over the next couple of years.” Pandemic measures to limit the spread of COVID-19 resulted in just 69 confirmed flu cases in 2020-2021 and only sporadic cases in 2021-2022, according to a recent update from the National Immunization Advisory Committee, which advises the Public Service Health Canada. regarding vaccine use. The pool of potential flu patients this fall and winter is larger as masks and social distancing rules have fallen, says immunologist Dawn Bowdish of McMaster University in Hamilton. “As a population we are ripe for the flu,” he said. “One of the reasons it seems to be spreading a little earlier than it would have in a pre-COVID kind of year is because there are so many vulnerable people who can harbor this infection.” Like Hota, she says the potential increase in traffic in the coming months is “a really big problem” for children under two who are exposed for the first time and are more prone to serious illness. The same is likely true for three- and four-year-olds who might otherwise have had the flu as babies or toddlers but were spared because of COVID-19 mitigation strategies, he adds. “Because we’re dealing with a bunch of kids who haven’t had a lot of stimulation … we can expect it could be really problematic for the young kids this year,” Bowdish said. WATCHES | Is it COVID or the flu? How to tell the difference:
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Dr. Samir Gupta reminds the public to know the symptoms of COVID and how to get tested properly as we enter flu season after Thanksgiving gatherings. He notes that a similar scenario played out last summer, when an outbreak of respiratory syncytial virus, or RSV, sent infants, toddlers and preschoolers to the hospital and strained pediatric health care resources. While myriad other pressures continue to weigh on the health care system — including ongoing COVID-19 infections that many experts fear will increase as well — it’s especially important to get the flu shot this year, Bowdish adds. In terms of the flu risk to the population as a whole, infectious disease expert Matthew Miller doesn’t expect a missed flu season to make us much more vulnerable than in previous years. Miller, director of the Michael G. DeGroote Institute for Infectious Disease Research at McMaster, says many adults can rely on some level of immunity built up from a lifetime of exposure to seasonal flu, including older adults who are generally not as strong. immune response as younger age groups. This immunity can last for years, even decades, if someone encounters a strain of flu that is closely related to something they’ve seen before. “During the swine flu pandemic, the elderly were disproportionately protected from death because the virus was so similar to the virus that caused the 1918 Spanish flu,” said Miller, also an associate professor of biochemistry and biomedical sciences at McMaster. “People who were very old and exposed to the 1918 Spanish flu and similar viruses released the year after that actually still had protection until 2009.” There have been cases where the same strain will recirculate for several years, but if it changes, that preexisting immunity becomes much less effective, Miller says. Thanks to pandemic measures that also protected most people from the flu, Bowdish says the types of flu circulating now are quite different than before the COVID-19 outbreak. “Because of all the social distancing (and) coverage, many lineages of the flu virus have actually died out,” he said. WATCHES | Experts prepare for busy flu season without pandemic restrictions:
Doctors prepare for busy flu season without pandemic restrictions
Schools, offices and doctors are preparing for a busy cold and flu season this fall now that most Canadians have resumed pre-pandemic activities. Scientists aren’t sure what to expect, but say Australia’s latest flu season may provide some insight. Clues to this season’s dominant strain can be found in what has been circulating in the southern hemisphere, Miller says, noting that we can more often expect to see the same version appear in Canada. “But that’s not always what happens in practice because, of course, between the Australian season and our season there are gaps and the dominant virus can change in between,” he said. But Miller said it’s possible someone who got sick in 2019 will have some protection this season, believing any changes to this year’s flu will be “modest.” While countries such as Australia, New Zealand and South Africa have been particularly hard hit, Bowdish says it is unclear whether this is because the virus itself has developed particularly problematic mutations, because vaccination rates have been low or because the vaccine has not been suitable very well with the strain. Danielle Paes of the Canadian Pharmacists Association points to a survey of 1,500 adults in August that found only 50 percent of respondents said they would be successful this year, six points below a survey in 2021. The margin of error is plus or minus 2.53 percentage points, 19 times out of 20. Paes says declining interest in the flu vaccine could also worsen the impact of the flu this season. A survey of 1,500 Canadian adults in August found only 50 per cent of respondents said they would like it this year, down six points from a survey in 2021. (Leah Hennel) Hota points to the resumption of many pre-pandemic activities as a major factor driving flu infections this season, noting that mask mandates have dropped, people have resumed travel and are huddled indoors again. “In previous years we’ve had public health measures and some sort of restriction on people’s movement or socializing or people’s ability to congregate,” he said. “It’s definitely different this year.”
