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Health care workers prepare for possible 'twindemic' this fall — a double whammy of COVID-19 and flu

 Dr. Douglas Fraser.
Dr. Douglas Fraser.

The body’s blood vessels are lined with tiny, super-soft “hairs” that wave around like tentacles in the blood. They normally keep platelets, the cells that form clots to stop bleeding, from sticking inside the vessels, because when one platelet sticks, more stick, until a potentially lethal blood clot forms.

“Why are critically sick COVID-19 patients clotting?” has been one of the biggest mysteries confronting doctors. This week, a London, Ont. team offered a potential answer: In response to COVID-19, the body’s immune system churns out enzymes that shear off these little sugar-coated hairs. The blood vessels become inflamed and exposed, allowing platelets to glob on, causing micro clots in the lungs and throughout the body.

In addition to the clotting mystery, Dr. Douglas Fraser and his co-authors identified six molecules that appear to predict which people with severe COVID are at the highest risk of death. It could mean knowing when to intervene earlier and more aggressively in people destined to have a very bad outcome, says Fraser.

“It also gives us an opportunity to have really frank and honest conversations with substitute decision makers and loved ones,” says the ICU doctor and lead researcher from Lawson Health Research Institute. How aggressive would they want us to be?

If backed up with more research, the twin studies could lead to better treatments for a new disease that’s about to converge with a familiar foe. What happens when COVID and flu collide?

Some have called the prospect of duelling epidemics a Dickensian disaster. Others are taking some comfort in the Southern Hemisphere’s freakishly mild flu season. “They’re testing really aggressively in Australia and they’re just not finding cases,” says Dr. David Buckeridge, a professor in McGill University’s School of Population and Global Health.

The Southern Hemisphere’s experience is, in some ways, “a good reflection that all of the good public health measures that people are continuing to practise, the hand washing, the physical distancing as much as possible, the use of non-medical masks and so on that help prevent or limit the transmission of COVID-19, would also work equally well for other respiratory infections, including influenza,” Dr. Howard Njoo, Canada’s deputy chief public health officer, said this week.

Others aren’t convinced we’ll get off so easily, noting that peak flu season in the Southern Hemisphere happened when most schools were closed. In Canada, classrooms are just starting to reopen. “Influenza is predictably unpredictable,” said Dr. Mark Loeb, a professor of pathology and molecular medicine at McMaster University.

“Almost nothing is known” about co-infection with flu and COVID-19, American epidemiologists Michael Osterholm and Edward Belongia write in Science . Most people remain vulnerable to the pandemic virus, they note, and if a COVID-19 surge in the fall overlaps with a surge in flu, the stress on hospitals could be crushing. However, it’s also possible the number of people infected with each virus will peak at different times.

Public health experts are pushing for an uptake in flu shots. In a Pollara survey in May of 1,912 Canadians, 57 per cent said they “definitely” or “probably” will get a flu shot, up from 45 per cent who claimed they had one last year. But a potential “twindemic” is creating unique challenges to getting the vaccine into deltoids. With many offices shuttered, there are fewer office flu clinics. Will there be sufficient PPE for vaccinators in pharmacies and other places? Will the public fear potential exposure to COVID-19 while lining up for shots?

The provinces and territories are being encouraged by the Public Health Agency of Canada to consider different strategies: multiple, smaller clinics instead of big ones, administering shots outdoors in parking lots or drive-thru clinics, mobile clinics in vans or buses, fly-in teams in remote and isolated communities — measures that could be a run-through for the day if and when COVID-19 vaccines become available.

“This year is going to be a little bit different because of the risks that COVID-19 poses to our staff. It’s very difficult to have that two-metre distance when you are in close proximity giving an injection,” said Victor Wong, owner of two Shoppers Drug Mart pharmacies in the Toronto area. “Initially there has been some concerns about safety, understandably, because COVID-19 is such a highly contagious disease. But I’ve taken steps to really reassure them we will have the necessary safety precautions.”

The provinces and territories have bumped up their flu vaccine orders in anticipation of increased demand, to more than 13 million doses, from 11.2 million last flu season. The composition of this season’s flu vaccine has been tweaked, but there isn’t enough information on currently circulating strains to know which will be dominant in Canada this fall and winter. Flu shots are generally 40 to 60 per cent effective if a decent match with the strains circulating.

Both flu and COVID can be deadly, particularly to older people and those with underlying illnesses. Studies suggest a dual or co-infection — flu, plus COVID-19 — is rare, but a risk. One of the key issues will be early testing, so that doctors know what they’re dealing with — is this flu or COVID?

There’s a huge overlap in symptoms but treatments differ. It’s a matter of testing early, and getting a diagnosis, Loeb says, and if there’s a surge in both viruses, it could overwhelm testing systems. Knowing which is which “will be an essential component for public health surveillance,” in addition to how sick people are managed.

The extent to which people keep social distancing and masking will be important for both COVID-19 and the flu. There’s control over that, Loeb says. “On the other hand there’s a lot of return-to-normal activities, like school,” which might make it more difficult to contain both.

In Ontario, a child who gets ill with symptoms of COVID-19 will be isolated and sent home, and one case in a classroom could shut down the class for 14 days.

“We’re seeing a spike in infections just as schools are opening up,” says Steven Taylor, a professor and clinical psychologist at the University of British Columbia. Historically, schools have been hotspots for flu and other respiratory infections, “and likely will be hotspots for COVID-19 transmission,” Taylor says, though countries with low virus rates haven’t seen significant transmission among school children.

“Schools will send children home if the school is unable to determine whether a child has COVID-19 versus a cold or flu,” Taylor says. “For many families that means parents will have to try to work from home.”

But McGill’s Buckeridge says there’s room for hope. “As far as we know people don’t transmit influenza virus unless they have symptoms,” he says. “It would be almost societally unacceptable right now to be walking around with those kind of symptoms. And that’s when you’re transmissible for flu. We would expect there to be much more prompt isolation of cases of infectious influenza” than usual, he says.

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Copyright Postmedia Network Inc., 2020

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