Figure 1: Schematic depiction of the COVID-19 rapid antigen tests available in Canada.
Step 1 – Specimen collection.
A nasal sample is collected using the sterile swab provided. Blowing the nose prior to swabbing, tilting the head back 70 degrees, compressing the nostril with the aid of fingers, and using circular motions while in the nasal cavity have been known to aid with collection.
Step 2 – Test procedure.
The swab is submerged in a buffer solution to extract the SARS-CoV-2 virus (if present). After a rest period, the resulting liquid is dispensed with the aid of a nozzle into the sample well on the testing device. The sample then moves through the testing device during which antigens present in the sample bind to antibodies in the device, forming antigen-antibody complexes. The reaction lasts for 15-30 minutes (depending on the manufacturer’s instructions) after which results may be read.
Step 3 – Results interpretation.
Two lines detected at the T (test) and C (control) lines of the test window indicate a positive result. This means the sample is positive for SARS-CoV-2 and the person is most likely infected. Positive results can be reported at local/provincial/territorial Public Health units or at independent initiatives such as The Rapid Test Tracker. If only one line at C (control) appears, the result is negative, meaning that the individual is most likely not infected. *It is important to note however that a negative result may also indicate that a person is infected but below the level of detection. That said, if symptoms are present, individuals should continue to isolate and follow local public health guidelines. The test may be repeated a few days later to re-ascertain infection status. No lines or a faint T line indicates an invalid test. A test cannot be used more than once.