As Alberta nears the end of March, the province still has not recorded a single lab-confirmed case of influenza.
Despite having done almost two and a half times as many tests for the flu compared to this time last year, Alberta Health Services statistics covering Sept. 27, 2020, to March 20, 2021, show zero cases. Last season the province saw 8,470 total cases recorded from Aug. 25, 2019, to May 2, 2020, including 1,534 hospitalizations and 39 deaths.
Dr. James Dickinson, a professor at the University of Calgary Cumming School of Medicine in charge of the Alberta community influenza surveillance program, said there isn’t an obvious reason why Albertans haven’t had the flu and a complete answer won’t be available until other provinces and countries get a chance to compare data at the end of the season.
There are several hypotheses. Alberta’s flu season starts earlier than other places and is often started by visitors travelling from the southern hemisphere where the flu season has just ended, Dickinson said.
But now, because of pandemic precautions, there is less travel.
“We’ve got very few people to bring it in and then, presumably, (with) those few that do bring it in it hasn’t been able to spread because of our social distancing and hygiene precautions,” he said.
Test, test, test
Each flu season a fraction of the people who show up in some doctors’ offices, hospitals, or now at some COVID-19 testing centres around the province, are tested for influenza.
The number of flu tests completed in Alberta from Aug. 23, 2020, to March 20, 2021, is approximately 107,820, according to Alberta Health spokesperson Tom McMillan.
The season before, from August 25, 2019, to March 21, 2020, 39,793 flu tests were performed.
“We have screened far more tests for influenza, which makes the current results all the more noteworthy,” McMillan said.
Alberta is not alone in its unique flu season. Across Canada, scientists have seen a dramatic drop off in flu cases. According to Health Canada statistics up until March 20 this season, only 66 influenza cases had been reported.
Keeping more respiratory illnesses at bay
Each year at the end of February the World Health Organization uses data on that season’s flu to help make a recommendation on the formula of the next flu shot. That gives scientists the six months to eight months they require to get the shot ready, Dickinson said.
He acknowledged that this year experts had “extremely limited data” to make their recommendation but said there is no way to know whether that means the next shot will be less effective than usual.
The COVID-19 public health rules aimed at slowing the spread of the pandemic — don’t gather in groups, wear a mask, stay home if you feel sick, wash your hands — all help to slow other illnesses like the flu.
“It’s not just stopped the flu, it stopped a whole variety of other respiratory infections that normally circulate in the winter season,” Dickinson said.
As a potential third wave of the COVID-19 virus nears in Alberta, the lack of some other illnesses landing people in the hospital is good news at a time when officials worry about the system being overwhelmed.
“In fact, in the pediatric hospitals, the usual winter (with) kids who get some sort of viral infection and then end up … admitted to hospital, that just hasn’t happened this year,” Dickinson said.
The test for the flu is different from that test for COVID-19 and there is no way that positive flu cases are somehow being confused for the pandemic virus, Dickinson said.
“These are very different. They’re very specific tests.”
He said Alberta’s experts are world-class.
“We have terrific virology staff who were really on top of this.”