Should I get a rapid test before a holiday gathering? We answer this and your other COVID-19 questions

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With the highly transmissible omicron variant becoming the dominant strain of COVID-19 in Canada, and more people planning to gather for the holidays, health experts are calling for expanded rapid antigen testing to mitigate outbreaks.

"We should flood Canada with rapid tests," said Dr. Isaac Bogoch, an infectious disease specialist at Toronto's University Health Network.

"There should be no rapid test sitting on a shelf, collecting dust in a warehouse. They should be in the hands of Canadians."

WATCH | Why are many rapid tests in Canada going unused?

Many people asked CBC News about rapid tests and their effectiveness amid concern about getting together with family and friends over the holidays, given the rise of the new variant of concern and spiking case numbers.

Here's what doctors and infectious diseases specialists say you need to know about these tests:

What is a rapid antigen test?

Rapid antigen tests use nasal swabs to detect viral proteins in a biological sample and can deliver results in less than 20 minutes.

These tests can aid in earlier detection of positive COVID-19 cases because they don't require the use of a lab to generate results.

Their main advantages are they can be inexpensive and are generally easy to administer.

WATCH | How rapid COVID-19 tests work:

How to take a COVID-19 rapid test

3 years ago

Duration 10:37

Respirologist Dr. Samir Gupta shows how to accurately use a COVID-19 rapid test. He also explains the role the test can play in our fight against the pandemic.

How do I use it?

If you're using a rapid test at home, health experts say it's important to carefully follow all the instructions in the kit.

"You take a swab, you put it up your nose, you swirl it around and then you add that swab usually to a little bit of a special solution that comes with the kit," said Dr. Raj Bhardwaj, a family physician and urgent care doctor in Calgary.

"Then you take a few drops of the liquid that you throw your swab around in and you drop it on to a little test."

When reading the results, Bhardwaj said there will beone line if you testnegative for the virus and two if you test positive.

The "C"and"T"on the side of the test are indicators and stand for "control" and "test."

What if I test positive on a rapid test?

If you receive a positive result, you'll need toreceive a polymerase chain reaction (PCR) test to confirm it.

The Public Health Agency of Canada (PHAC) says positive results from rapid tests should be considered "presumptive positive" until a PCR test can confirm whether the novel coronavirus is present or not.

PCR tests evaluated in a lab remainthe primary method for diagnosing COVID-19 in Canada. They are highly accurate and sensitive to small amounts of the virus. It typically takes 24 hours to receive a result from a PCR test.

How accurate are rapid tests?

A rapid test is most accurate when a person has COVID-19 symptoms, said Dr. Fatima Kakkar, a pediatric infectious disease specialist and doctor at the Centre Hospitalier Universitaire Sainte-Justine in Montreal.

Under these circumstances, a rapid test produces correct results 80 to 90 per cent of the time, she said.

If you're asymptomatic or in the early stages of infection, the positivity rate drops to between 35 to 50 per cent, according to Kakkar. That's because you may not have a lot of the viral protein in your system for the test to detect.

• Have a coronavirus question or news tip for CBC News? Email: covid@cbc.ca

"A negative test should not be taken to be the absence of infection, and a single test is much less accurate than doing repeated tests," said Dr. Cdric Yansouni, an infectious disease physician and associate director at the J.D. MacLean Centre for Tropical Diseases in Montreal.

If you do repeated tests, it not only reduces the potential of a false negative but also the chance of human error in how the sample was gathered.

Rapid tests are far less sensitive than PCR tests, adds Yansouni, meaning a person typically needs a high viral load for it to show a positive result.

Should I use a rapid test to attend holiday gatherings?

While a rapid test can be an extra safety measure for holiday gatherings, Canada's chief public health officer hasrecommended it be used in conjunction with other precautions, such asgetting a booster shot when you're eligible, limiting your contacts and wearing a medical-grade mask.

"Make sure that you know that these tests are not perfect," Dr. Theresa Tam said at a Dec. 10 news conference.

Shesuggested peopleseek a second rapid test to ensure the results are correct.

If you choose to take a rapid test, it's important to use it quite close to the actual event, said Bhardwaj.

For example, if you plan to attend a Christmas dinner, you should take a test that afternoon. Not a few days prior.

"The amount of, or the degree of, contagiousness can change quite a bit over even a couple of days," Bhardwaj said.

But it's also important to keep in mind the possibility of false negatives in those who are asymptomatic, which is why Tam suggestedusing the test as only one of several precautionary measures when deciding whether to attend a gathering.

I want to havepeople over. How can I keep it safe?

For those planning aholiday gathering, epidemiologist and cardiologist Dr. Christopher Labos suggestedensuringall guests are vaccinated including children age five and up who are eligible for their first dose andpre-screened for symptoms.

"If you can do all of those things and keep the gathering small, it's unlikely that someone would have COVID," Labos said.

Yansouni said hosts should also be mindful of ventilation.

"If you can do an event outside instead of inside, that makes sense," Yansouni said.

As peopledo moveinsideto escape colder weather, experts have beenurgingCanadians not to forget about wearing masks to protect against COVID-19, and also to consider what type of mask to use.

PHAC put out new mask guidance with a shift toward recommending medical masks and respirators, such as N-95 or KN-95 masks, instead of cloth ones.

Yansounialso had amessageforthose who find they areshowing symptoms before an event:"be kind to your family and friends.Stay home."

How often should I take a rapid test?

Rapid tests shouldn't be used as a one off, said physicians including Dr. Jesse Papenburg, a pediatric infectious disease specialist at the Montreal Children's Hospital.

If you're experiencing any COVID-19 symptoms, you should take the test at least twice waiting a day or two in between.

"By repeating it 24 to 48 hours later, then you're getting that extra security that you know you're not missing somebody who's on the upswing of infection," Papenburg said.

For screening in workplaces, the Ontario and B.C. governments advise rapid testing be done two to three times a week for asymptomatic people in areas with high rates of infection.

Where can I get one?

Accessibility of the tests continues to evolve. Ontario started offering free rapid antigen tests as of Wednesday at pop-up sites, including malls and libraries, as well as some liquor stores.

Ifyou live in New Brunswick, Nova Scotia or Saskatchewan you can get free rapid tests at health centres, pop-up testing sites or libraries.

"Nova Scotia is a model for how to get rapid testing out into the community," said Bogoch, noting that other parts of the country should be looking very closely at the province's plan.

Take-home kits are also being offered to students and children in Alberta, Ontario, Saskatchewan, Nova Scotia, Prince Edward Island and Quebec.

In B.C., non-profits, charities and Indigenous community organizations can access free tests through the Canadian Red Cross.

In Manitoba, rapid tests are available for staff working directly with children at Fast Passtesting sites.

Meanwhile, parents in Northwest Territories can volunteer to have their children included in the pilot at-home COVID-19 testing program.

Health Minister Jean-Yves Duclos said at a Dec. 10 news conference that more rapid tests will be made available across Canada to fight increasing COVID-19 cases and the ongoing threat of omicron.

WATCH | Health minister discusses rapid tests distribution:

Health minister says more rapid tests being made available to provinces and territories

3 years ago

Duration 1:52

Health Minister Jean-Yves Duclos says more rapid tests will be made available to provinces and territories to fight rising COVID-19 caseloads and the threat of the omicron variant.

As of early December, the federal government had purchased and shipped over 94 million units of rapid tests across Canada.

The federal government, as well as some provinces and territories, are providing free rapid tests to organizations so they can complete regular screenings of their employees.

Travellers entering Canada may receive a self-swab kit to complete within 24 hours, if they are selected for mandatory randomized testing.

At-home tests are only recommended for those aged three and up.

How much do they cost?

Aside from the free tests being made available, you may have to pay for one, dependingon where you live.

"The federal government has got literally millions of these tests and has distributed them to the provinces and then the provinces are using them differently," said Bhardwaj. "So some provinces are making it very easy to access [the tests]."

While others are not, he added.

"It's frustrating that they're not available for free everywhere," he saidin an earlier interview with CBC News.

Some tests are available for roughly $40 in pharmacies in several provinces across the country, such as Ontario.

With files from Lauren Pelley, White Coat, Black Art