Coronavirus: What you need to know about different types of Covid-19 tests and when to use them
- A doctor who specialises in viral infections explains the different types of test kits available, and their pros and cons
- PCR tests remain the gold standard; ART tests have a higher chance of false positive results
When should you take a PCR nasal swab and how is it different to an ART test? Photo: ShutterstockThere are various types of Covid-19 tests that people may choose from to find out if they are infected with the virus.
Dr Matthew Binnicker and the team at Mayo Clinic Laboratories help break down the different types of Covid-19 tests and when to use them.
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Polymerase chain reaction (PCR) test nasal swab
What is it?
This test looks for the virus’ RNA in a patient’s sample. A sample is collected by inserting a swab into a person’s nostril and taking cells from the back of the nose. Some lab tests allow for patients to spit into a tube to get a saliva sample.
When should you take this test?
Make an appointment with an approved health care provider or testing centre that offers PCR tests if you have been exposed or if you are experiencing Covid-19 symptoms.
When can you expect results and how accurate will they be?
You can expect to receive your results within 24-72 hours. The PCR test is the gold standard when it comes to Covid-19 testing.
At-home nasal swab with lab-based PCR test
What is it?
This is a similar type of test used at the health care provider, but you collect the nasal swab yourself and mail it to a laboratory to be analysed.
When should you use this test?
Use this test after exposure or when you begin experiencing symptoms.
When can you expect results and how accurate will they be?
At-home tests can typically take anywhere between two to four days for results. Since these tests are PCR tests performed in a laboratory, these results have higher accuracy than at-home antigen tests.
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Saliva PCR test
What is it?
Instead of a nasal swab, saliva sample is collected and mailed off to a laboratory to be analysed. Similar to swab tests, saliva is a specimen that can be collected for polymerase chain reaction testing. Saliva is typically easier – and more comfortable – to collect from a patient, compared to a nasal swab.
When should you use this test?
Use this test after an exposure or when you begin experiencing symptoms.
When can you expect results and how accurate will they be?
At-home mail away tests can typically take anywhere between two to four days for results. Since these tests are performed in a laboratory, these results have a higher accuracy than at-home antigen tests.
Rapid at-home antigen tests
What is it?
The rapid antigen tests (ART) detect certain viral proteins in the nasal sample.
When should you take this test?
Timing is key with this test. Try to take it on the day of the event you are attending, which requires a negative Covid-19 test result. That is going to give you the best information of whether you have high amounts of the virus in your system at that time.
How does this test produce results?
Using a nasal swab, antigen tests can produce results in 15 minutes.
When can you expect results and how accurate will they be?
These tests are available for purchase where at-home tests are sold. These tests are faster and less expensive than PCR tests, but there is an increased chance of false positive results. If an at-home antigen test is negative, continue to wear a mask in public settings, around those who are unvaccinated or those who are at a higher risk for serious infection if they catch the coronavirus.
If an at-home test is positive, you should have a lab-based PCR test performed the same day or the following day to ensure the case is tracked by health officials and to connect you with a health care provider who will determine if treatment is necessary.