Numerous mainstream media reports have labeled the saliva tests as ‘87% accurate’, based on a report by the Peter Doherty Institute, which developed them. However, what that report makes clear is that the accuracy rate is comparative to PCR testing only, and does not indicate that it can identify all coronavirus cases with 87% sensitivity. While PCR tests are incredibly accurate in a laboratory setting, recent research suggests sensitivity in a clinical setting is affected by the timing and estimated to be only around 70%.
What actually happens during a COVID-19 nasal swab test? How does COVID-19 testing work?
The person conducting the test will insert a long stick with a very soft brush on the end — kind of like a pipe cleaner — up your nose and twirl it around for a few seconds. The soft bristles will collect a sample of secretions there for analysis. The swab has to go pretty far back because cells and fluids must be collected from along the entire passageway that connects the base of the nose to the back of the throat to get a really good specimen. The body is not used to having an object in that area, though, so it creates a lot of very odd sensations. For one thing, it activates the lachrymal reflex, which means it’ll bring tears to your eyes if it’s done correctly. I wouldn't go so far as to say it hurt, but it is uncomfortable. Since the swab will also touch the back of the throat, it may also trigger a gag reflex.
Are there any other types of COVID-19 tests available?
Yes, tests can be performed on other less invasive specimen types, such as a throat swab. But they are less sensitive than the COVID-19 nasal swab test. Saliva is another specimen type that is being explored, but the jury is still out on that one. The preliminary data look really promising. But we’re still waiting on larger studies to confirm these initial findings. In addition to nucleic acid testing, which detects a virus’ genetic material, there is also antigen testing, which detects the presence of viral proteins that spur the production of antibodies, or the immune system’s response to invaders. While antigen tests are quicker, they are also much less sensitive than nucleic acid tests. So, while a positive antigen test is informative, a negative result would need to be confirmed by the more sensitive nucleic acid test. It’s important to obtain the best possible specimens, so COVID-19 nasal swab testing that includes nucleic acid testing.