Updated guidance on using rapid antigen tests
The Ontario Science Table has advised that rapid antigen tests are less sensitive for the Omicron variant compared to the Delta variant in nasal samples, especially in the first 1-2 days after infection. However, rapid antigen tests can more reliably detect infectious cases of the Omicron variant in combined oral-nasal samples. Therefore, when doing a RAT you should:
- NOT eat, drink, chew gum, smoke, or vape for at least 30 minutes before collecting the sample.
- Insert the soft swab tip between both inner cheeks and lower gums and turn the swab a few times.
- Then, rub the soft swab tip on your tongue as far back in your throat as you feel comfortable or you may choose to swab the back of your throat and tonsils. You can use a mirror to help see where to rub your swab.
Watch this helpful video to find out how to best use the RAT or refer to the Ministry How to Collect a Sample fact sheet for pictorial instructions for collecting a combined oral and nasal specimen.
In light of currently very high SARS-CoV-2 transmission rates in Ontario and the limited sensitivity of rapid antigen tests for the Omicron variant, a single negative rapid antigen test result cannot reliably rule out infection; a single negative test result is not conclusive and should not be used as a green light for abandoning or reducing precautions. Conversely, in this context, an individual with a positive rapid test result should view it as a red light and should be considered and managed as a case of COVID-19 and should immediately isolate; additional confirmation by polymerase chain reaction (PCR) is not necessary in most settings.