Quirks & Quarks

How we test for the COVID-19 virus — and how can we do it faster?

A chemist gives us an understanding of why COVID-19 tests take so long, and how lab tests are different from the new automated tests popping up on the market

New automated tests are promising for quick results, but can’t replace current lab tests

A nurse in Chessington, England takes a swab at a Covid-19 Drive-Through testing station. (Dan Kitwood / Getty Images)
Listen11:06

As the number of infections rise around the world, some countries are faring better than others when it comes to containing COVID-19. 

One of the key differences involves vigorous testing programs, something that Prime Minister Justin Trudeau recognized last week.

"We know that massive testing has been part of the solution in places that have managed to contain or slow the spread of COVID-19," he said in his daily update on Tuesday. "Testing is not just about giving people peace of mind, it's an essential element for the public health response that will keep us all safe."

So then the simple solution seems to be that we should all be testing as much as possible, right? Well, it's not quite so easy. 

"Presently, we're doing over 10,000 tests a day and they vary from province to province. I would say that we probably need to be doubling, if not tripling, that number," Canada's Chief scientist Mona Nemer said in an interview with Bob McDonald last week.

Recently Canada's health minister signed an order to ramp up the approval process for new tests.

In other countries there are new automated testing technologies coming up seemingly every day, ones that promise to get results in a matter of minutes as opposed to days. While we don't yet know when automated testing kits will be coming to Canada, there are still many questions about how these tests work, and whether they are as accurate as the traditional lab testing.

To help us get a better understanding of the current state of COVID-19 testing, Quirks & Quarks host Bob McDonald spoke with Jen Heemstra, an associate professor of chemistry at Emory University.

This interview has been edited for length and clarity.

MCDONALD: What part of the coronavirus are the tests looking for?

HEEMSTRA: If we think about viruses they have a structure that's a little bit like an egg. You have this hard outer shell. And for viruses, that's made up of a molecule called protein. And then on the inside of that shell is a different molecule called RNA. The RNA basically encodes all of the instructions that that virus needs in order to infect a cell and go to work, you know, turning that cell into a factory to make more copies of the virus. So the virus can replicate and launch an attack on the person who's infected. 

What the tests are doing is basically cracking open that egg, and pulling out that RNA from that virus code, and then using special probe molecules that can go and bind to the regions of that RNA molecule that have unique codes that are only found in COVID-19. And then if they bind, then that sets off a reaction that then generates a signal that can indicate a positive test result.

Dr. Jen Heemstra and graduate researcher Colin Swenson in their lab at Emory University. (Kay Hinton / Emory University)

Why does it take several days to get results from these tests?

So when we think about the laboratory tests, there's a lot of time spent taking a sample, sending it to a lab, and then you need specialized people with specialized equipment in order to perform the reactions to pull that RNA out of the protein shell.

But in the case of these [new automated] tests that we can use right in a doctor's office, all of that happens right inside the test and so it's just a lot faster because you save all of that time of having to take your sample to the lab.

[Another] difference between the automated tests and the lab tests is a lot like the options we have with pregnancy tests. If someone is pregnant, they can go into their doctor's office, get their blood drawn and the doctor can figure out exactly how much of the pregnancy hormone they have in their bloodstream and they can tell them all sorts of things, but then that home test just gives you a yes or no. 

And so the COVID-19 tests are exactly the same. If you have the one that is sent off to the lab, they can tell you with fairly good accuracy how much virus there was in the sample. And so then that might be able to provide some indication of how long someone's been infected or how severe of an infection they have. Whereas the tests that you can do right in a doctor's office, those are just looking to see if you have over a certain amount of that RNA that's detected, and then it just gives you a yes or no.

A UK company claims this new blood test can give a result for Covid-19 within 10 minutes. (Christopher Furlong / Getty Images)

Are these automated tests as accurate as what's being done in the lab?

We don't have data yet on the [new] COVID-19 tests that are being used. But interestingly, we can look at those same testing platforms as they've been used for detection of influenza, and the numbers look pretty good. There's a study a few years ago that showed that compared to the laboratory tests, it's 10 per cent or so, or less, of the positive cases that that would be detected using the lab test.

How quickly do you think these fast tests can get on the market and start giving us that critical information?

The good news with these kits is that it's not a whole brand new system that's being invented. A lot of these companies have had these rapid diagnostic tests out on the market, these instruments are currently being used to detect all sorts of other types of infections.

And so really what's needed in order to get the scale up for the COVID-19 testing is just the individual little cartridges or whatever it is that goes with that instrument and has those special probe sequences for the COVID-19 RNA. And thankfully those are actually fairly simple to make. Companies should be able to scale these up relatively rapidly and really be able to dramatically increase the amount of testing that we're able to do.

Written and produced by Amanda Buckiewicz

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