The flu season of 2021 was notably absent. By April’s end, Canada recorded merely 72 cases of influenza, a staggering reduction compared to the typical 50,000 cases seen in a standard year. This raises the question: what led to this decline, and what implications does it have for our future?
A significant reduction in influenza cases
Dr. Earl Brown, PhD, an emeritus professor of virology at the University of Ottawa, remarked, “We’ve never encountered a decrease like this.”
While there were rhinovirus infections present—responsible for many common cold cases—Brown noted that many other viruses affecting the respiratory tract were virtually absent.
This pattern has not only been observed in Canada; numerous countries have reported significant reductions in flu activity, with the United States seeing a remarkable 98 percent drop.
This shift aligns with the emergence of the COVID-19 pandemic, leading many to speculate if the two events are interconnected.
Controversies in testing for COVID-19 and influenza
Some speculate that the decline in flu cases might not reflect a true decrease, but rather an underreporting phenomenon as healthcare facilities focused their resources on the pandemic response.
This theory seems valid in some nations, where the submission of specimens for flu testing in the U.S. dropped by 61 percent.
Contrastingly, Canada experienced a surge in flu testing, performing nearly four times the average amount, yet recorded virtually flat flu cases.
There are concerns regarding the reliability of testing protocols. Some assert that specific COVID-19 tests can mistakenly identify influenza instead of the coronavirus.
However, Canada employs a specialized PCR test uniquely designed to detect COVID-19’s genetic material, minimizing the risk of false positives due to the flu.
Dr. Gerald Evans, chair of infectious diseases at Queen’s University and former president of AMMI Canada, emphasized that the notion of under-testing in Canada does not hold water. “We actively sought influenza and other seasonal viruses, and although we observed high COVID-19 instances, influenza was notably absent,” he stated.
Underlying reasons for the flu’s disappearance
The drastic decline in flu cases during the last season cannot be solely attributed to the increased use of sanitizing products; it is more connected to reduced air travel.
Evans clarified that the influenza virus requires human movement for transmission and mutation, typically spreading from the southern hemisphere in winter to the northern hemisphere later on.
“Influenza relies on travel for dispersion to new areas,” he noted. “The pandemic’s limitations on travel resulted in significantly lower initial flu numbers.”
Once the flu did appear, local travel restrictions and closures inhibited its propagation, with Canada’s flu surveillance indicating “no community circulation of influenza” during that season.
According to Evans, multiple factors contributed to the mere 72 recorded flu cases in a year when typically there would be tens of thousands.
But just because this season was an anomaly doesn’t mean that influenza and other respiratory viruses have vanished altogether.
The potential resurgence of viruses
Preventive measures like social distancing, lockdowns, and halting international travel have significantly minimized flu occurrences this past season but may lead to challenges ahead.
Brown cautioned, “Emerging flu variants that appear distinct to our immune systems could present new challenges. Prior exposure to earlier strains helps in immunity, but drastic changes in the virus might evade that protection.”
“We may see a decrease in our flu immunity,” he added, implying a higher likelihood of contracting respiratory infections we are typically accustomed to. While it may not be catastrophic, the expectation is for an increase in flu transmission rates.
Adjusting to a new norm
Evans acknowledged, “Many of the measures implemented for COVID-19 have also shielded us from influenza and other respiratory illnesses. The key question remains how much of this behavior will persist.”
By the time this article reaches you, travel and community restrictions may have been fully lifted. Evans noted, “People are weary of restrictions; they’d prefer a return to normalcy without masks.”
Nevertheless, he hopes that individuals will remain conscientious about their health and take precautions when feeling unwell.
“As a specialist in infection control, I would be delighted if increased handwashing became commonplace,” he chuckled. “The use of masks may continue, particularly during winter or if someone shows cold or flu symptoms.”
“If more of the public can adopt these hygiene practices that emerged during the pandemic, it would yield benefits for public health for years to come,” he opined, emphasizing their lasting positive impact.
