Rapid COVID-19 tests: When to take one, and what to do if it’s positive

The holidays are fast approaching, and many Canadians are trying to get their hands on COVID-19 rapid antigen tests for added protection this season.

Governments and health officials have been urging the use of rapid tests as the Omicron variant spreads, threatening to worsen Canada’s COVID-19 pandemic over the winter.

But with more rapid tests flooding the market now, questions have swirled around their use: When should rapid tests be used, and what happens if someone tests positive?

Here’s what you should know.

Rapid antigen tests come with a nasal swab that a person can use to test themselves for COVID-19.

The tests are not as thorough compared to lab-based molecular testing, like the polymerase chain reaction (PCR) test, but they produce results faster.

To date, Canada’s rapid testing strategy has generally focused on long-term care homes, schools and workplaces. Some provinces have limited the general public and people who are asymptomatic from accessing the tests.

But as the Omicron variant takes hold and governments, in turn, expand the use of rapid tests, more Canadians should consider getting these tools, said Jason Kindrachuk, assistant professor of medical microbiology and infectious diseases at the University of Manitoba.

“Omicron has very much shifted the playing field for us … when you look at how quickly things have progressed over the last three weeks since Omicron was first identified, it’s been a very rapid progression,” he told Global News.

“We need to be able to utilize anything we can at this point to pinpoint where the virus is, and rapid tests certainly fill a very necessary void in that.”

Unlike molecular tests, rapid antigen tests work by checking for viral proteins in a person’s body. If a person has a lot of COVID-19 proteins in their system and is infectious, the test will come back positive, Kindrachuk said.

Therefore, rapid tests are “very time sensitive” and can tell someone if they’re infectious right now.

“(In) that moment in time, it gives you a good indication of whether or not you are likely infectious,” Kindrachuk said.

“That doesn’t necessarily mean a day later, or even 12 hours later … that you’re not going to be moving into that infectious period, and I think we have to be very transparent on that idea as well.”

Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital, told Global News a good example of rapid test use would be taking one before a small gathering.

For example, if all guests were to take a test a few hours before a function and test negative, you would have an “added layer of protection.”

“It’s a layer of protection in addition to vaccination, better-ventilated rooms,” he said.

“Obviously, people aren’t going to be wearing masks if they’re sitting down to eat, but we know masks are also helpful if you’re not in a place where you’re having dinner with each other.”

Dr. Alex Wong, an infectious disease physician in Saskatchewan, agrees.

COVID-19 proteins fluctuate in a person’s body with time, and since rapid antigen tests work by looking for those proteins, it’s best to take it closer to an event, Wong said.

“Ideally, your test would be done as close to your group gathering as possible because the amount of virus (in your system) changes quite quickly,” he said.

“If you do a test in the morning before you go to work, and then by the evening when you’re ready to go for your little party or whatever, you could have certainly enough virus at that point … (that) there could be a significant change the rapid (test) will be positive.”

Sarah Mostowich, project lead for the StaySafe Initiative, a pilot project that provided rapid test kits in Waterloo, Ont. earlier this year, told Global News Canadians should use rapid tests more frequently if possible.

“Find a way to incorporate it into your daily routine,” she said.

“Like you wake up in the morning, you brush your teeth, you take a rapid test and make sure you’re doing that two to three times a week so that you can detect in yourself early if you have COVID before you spread it to others.”

Your rapid test results are in: it’s positive. What should you do next? According to Mostowich, the first thing you should do is self-isolate.

Cancel your plans, and try to get in for a molecular test to confirm your results, she added. You can also contact anybody you might’ve seen recently to give them a heads up, but public health officials will also provide extra guidance after you get tested.

“PCR is kind of the gold standard when it comes to accuracy on tests and knowing for sure if you have COVID,” Mostowich said.

“Whereas rapid tests, while still fairly accurate, are just a preliminary positive if you get that positive result.”

Molecular COVID-19 tests like the PCR option take longer to produce results, and work by going down to the genome level of the virus. They can detect the virus before someone becomes infectious, Kindrachuk said.

However, demand for molecular COVID-19 tests has been increasing in parts of the country; Ottawa Public Health told health workers in a memo last week that virus testing is no longer available to everyone “in a timely manner” due to a surge in demand.

In Peterborough, Ont., the public health unit is encouraging residents to report positive test results from rapid tests online to help track cases in the community.

With that in mind, Kindrachuk said governments need to get more rapid tests in Canadians’ hands so they can better reduce the spread of the virus.

“We have to ensure that there’s equity in access to these tests and that the tests are not only going out to those that can afford to purchase those tests,” he said.

“If we want to be able to utilize tests like these to be able to get control of the situation, we have to ensure that we are able to make them available to everybody in our population as well.”

As Canadians go through the holiday season and the new year, Mostowich echoes Kindrachuk’s comments that rapid testing needs to become more common in people’s lives.

“It’s incredibly empowering for people to be able to see if they have COVID and use that as an extra measure of detection to help keep themselves and their families safe,” she said.

“As much as everyone can have regular access to rapid tests, it’s something that people should be incorporating into their daily lives and as part of their regular routine.”

— with files from Ashleigh Stewart and The Canadian Press