The No. 1 question on the minds of many Manitobans is why the province doesn't test broad swaths of the population for the presence of the virus that causes COVID-19.

The short and discouraging answer: Manitoba simply can't, at least not at the moment.

Neither can any other Canadian province — and not because of a lack of interest in doing so.

The capacity simply does not exist, as frustrating as that must be to anyone aware the World Health Organization has recommended widespread testing as a means of slowing the spread of the virus formally known as SARS-CoV-2.

Most people infected with this new coronavirus develop respiratory symptoms of some sort. Some of them do not.

The idea behind widespread testing is it allows health authorities to quickly identify people carrying COVID-19 and then isolate everyone they contacted or may have contacted.

In theory, this is Epidemiology 101. In practice, it's all but impossible in Canada right now, thanks to equipment and supply shortages in some jurisdictions, test-processing bottlenecks at diagnostic labs and a limited supply of technicians capable of conducting genetic testing for dangerous pathogens.

In some parts of Canada, there's been a shortage of the long, skinny swabs used to collect samples from deep within nose-and-throat passages.

In Manitoba, Cadham Laboratory was handcuffed for days by a shortage of one of the chemical compounds used as part of a process known as polymerase chain reaction (PCR) testing, where genetic material is extracted from viruses and then copied into quantities that can be more easily identified.

There are only so many samples that can be tested using a PCR machine at any given time. There are also only so many technicians capable of operating them.

This is why Dr. Brent Roussin, Manitoba's chief public health officer, said technicians are working day and night in shifts at Cadham lab to process COVID-19 tests as quickly as possible.

This week, Roussin said the province found a way to get around a shortage of reagent compounds that hampered provincial testing efforts at the lab. The result of this workaround was 734 tests conducted Wednesday, more than double the number a few days before.

As of Thursday, 5,606 Manitobans had been tested for COVID-19. This places Manitoba in the middle of the Canadian pack, in terms of processed tests per capita.

Also on Thursday, Roussin announced the province has broadened the categories of people who are eligible to be tested.

Manitoba now plans to test all returning travellers with respiratory symptoms, anyone in an intensive care unit or personal care home with respiratory symptoms, any health-care workers with these symptoms and anyone with symptoms on a First Nation, in a prison or in a remote location such as a work camp.

All of these people, taken together as a population, make up a portion of the Manitobans with respiratory symptoms at any given time. There are plenty of other people suffering from coughs who fear they may have COVID-19 but are not eligible to get tested for the disease right now.

Social media in Manitoba are awash with complaints from worried people demanding to be tested as part of an understandable desire for peace of mind.

Over the past two weeks, Roussin has repeatedly attempted to ease their concerns by noting the best thing a symptomatic person can do is remain at home for two weeks, if they don't require medical attention.

If they leave their homes to see a doctor, they could conceivably spread the virus, he has explained. He repeatedly stressed quarantine is just as important as testing, when it comes to containing the virus.

This approach amounts to a form of harm reduction, said Jason Kindrachuk, a viral pathogenesis professor at the University of Manitoba and the Canada research chair in emerging viruses.

'Would love to see more testing'

"I think all of us across the board would agree that we would love to see more testing being done and basically adhere to what the WHO suggestion was — to basically test, test, test and test everybody possible," Kindrachuk said earlier this week in an interview.

"We would love to see more testing. But I think at the same time we know that there are caveats to that," he said.

"Ultimately what we need to be able to do is get people that are showing mild symptoms of disease isolated, because it allows us some level of protection from allowing the virus to continue to transmit — and then still allow for the available testing that can be done to be focused on those patients that are most likely to be transmitting or require medical care."

This is why sick returning travellers, health-care workers, people in intensive care or people in remote locations are being prioritized right now.

These are the patients at the highest risk of transmitting the disease to other people. If tests have to be rationed, it makes sense to test these people first.

The need to ration is part of what Kindrachuk called a "long game." Like it or not, Manitoba is just starting to climb a COVID-19 curve that may take months to settle if physical-distancing efforts are successful.

"We know the testing at least has to be maintained through that period," Kindrachuk said.

"So I think that there is some concern about trying to ensure that there are reasonable supplies to be able to carry us through that period, to be able to maintain the tests that are going to be needed for people that are displaying obvious symptoms or people that are the most critically ill."

The downside is the number of known cases of COVID-19 may not reflect the actual presence of the disease in Manitoba.

"Since we don't yet have the capacity for mass population testing we really don't know the prevalence rate," said Steven Lewis, a Saskatoon-based health policy expert.

Canada could increase the testing rate by enlisting other labs and technicians, Kindrachuk suggested.

"I worked in West Africa during the Ebola epidemic on the front lines, leading diagnostic efforts. There are a lot more people like me that, if and when it's needed, we will be there," he said. "We have equipment across the country that we can repurpose specifically to help with with diagnostics."

This might require some easing up on regulations, as pathogens such as COVID-19 are typically tested within highly secure labs.

True mass testing, however, may require a test that doesn't rely on PCR machines. Other countries have utilized these tests.

"What's likely going to happen is that over the next few months we're probably going to see more diagnostic tests. They'll be pushed through the U.S. FDA for emergency-use authorization and that will ultimately get deployed in the field," Kindrachuk said.

"We'll hopefully be able to to reduce some of the burden that we're already seeing."

Ultimately, testing would not matter if every ​​​​Manitoban — healthy or symptomatic — stayed at home for two solid weeks.

Roussin is not just trying to calm the public by praising the benefits of physical distancing. He's prescribing the simplest course of action to contain a contagious disease.

Besides, whether you test positive or not, the outcome is the same if you're not sick enough to require intensive care: You stay at home.