As of Wednesday evening, Alberta had completed just over 35,000 COVID-19 tests — more than any other province in Canada — but, like many jurisdictions, it is now changing its protocols of who gets a test, in light of limited amounts of testing supplies.

"We only have so much testing capacity," the province's chief medical officer of health, Dr. Deena Hinshaw, said earlier this week.

As a result, Hinshaw said, the province is now shifting its criteria for who gets tested for COVID-19, focusing more on the people who are most at risk and on health-care workers.

The province is not at imminent risk of running out of testing materials, she said, but the existing inventory and the expected availability of new materials was part of the reason for the change.

"All the supplies involved in testing, from the swabs to the reagents, are constantly being assessed in terms of the stock that we have and the demand that we have on the system," Hinshaw said.

Lynora Saxinger, an infectious disease specialist at the University of Alberta, said that when materials such as reagents — the substances used to conduct genetic analysis and identify COVID-19 in a lab — are limited, then "practical triaging" is necessary.

"Change just means we're having to roll with the punches," she said.

"I think the initial phase of testing that was done did give us a better idea on things, and I think it guided the public health response here, where we've seen increased social-distancing measures," she added.

"But we're doing them faster than a lot of places. So I think the testing we've had has set us up reasonably well, and I think that focusing the testing right now is a necessary move. And I'm very certain that if any more availability of testing reagents and kits and materials happens, that there would be a desire to expand the testing again."

Specimen collection kits to be used for swab testing citizens for COVID-19 are stacked on a table at a drive-through test site in Jacksonville, Fla., in this file photo. (Bob Self/The Associated Press)

Other provinces are dealing with the same challenge.

Ontario Premier Doug Ford has linked that province's huge testing backlog to a lack of reagents and said health officials are doing everything they can to get more of the chemicals. Ontario has one of the lowest per-capita testing rates among the provinces.

In Manitoba, chief public health officer Dr. Brent Roussin told reporters earlier this week the biggest issue with increasing testing capacity in that province is the reagent, noting there is a global shortage. Manitoba's Cadham Provincial Laboratory has been producing its own reagent, he added, which he hoped would increase testing capacity by later in the week.

On Thursday morning, Roussin announced Manitoba would increase its COVID-19 testing to include more symptomatic people.

Alberta shift serves dual purpose

Alberta's new testing protocol means travellers who returned to the province after March 12 and have only mild symptoms will no longer be tested for the virus and, instead, simply be instructed to self-isolate.

"The most important thing anyone can do if they have mild symptoms isn't to get tested — it's to stay home and self-isolate," Hinshaw said.

"This is consistent with the approach happening across Canada. It will enable us to strategically use our testing resources."

Alberta chief medical officer of health Dr. Deena Hinshaw updates media on the COVID-19 situation in this file photo. (Jason Franson/The Canadian Press)

Testing will be prioritized for people hospitalized with respiratory illness and residents of continuing-care facilities.

Health-care workers will also be a priority for testing, which Hinshaw said serves a dual purpose.

"If they are not positive for COVID-19, it helps them get back to work more quickly," she said.

"It also helps us to test some individuals who have not travelled, so we have a better understanding of where there may be spread in our communities."