How reliable are self-tests? | EOS Science

Marc van Ranst recently tweeted: “Be careful with false-negative rapid tests for omicron if you take a nasal swab early in the infection process.” A throat swab is often positive. That raised some questions. We introduced them to Elke Wollants from KU Leuven. She is related to Laboratory of Clinical and Epidemiological Virology of the Riga Institute.

“Throat swabs are longer and thicker than nose swabs,” she says. ‘but you are It does not require a throat swab at all to take a throat sample. You can also use a nasal swab for self-testing kits that you get from your pharmacist as a throat swab. The squeegee comes out of the package, and first goes to the throat from the back, brushing your throat well on the uvula and on the sides, and then you go with the same swab in your nose. This makes the self-test more reliable. Especially with the omikron variant, because it’s first in your throat and then in your nose. It is about contracting the virus wherever it is.

“Of course nasal swabs have not been validated for this purpose, and FAMHP would certainly advise against using them as throat swabs. But we’ve heard that many people test negative with a nasal swab and a positive test with a throat swab. So it definitely works! We definitely recommend doing this, because there’s no point in just wiping your nose anymore.“

How reliable are self-tests in general?

Self-tests are reliable, but not as sensitive as the PCR test. But this is also not necessary, because if you are very positive, it will definitely show.

Is it true that a self-test only has a reliable result if you have symptoms?

“No, if the virus is strong you will catch it whether you have symptoms or not.”

Do self-tests lead to more false positives than false negatives?

‘never! False positive results are rare. If you see the second line sparkle, you can be sure that you are positive. False negative results are more common because they are not as sensitive as PCR tests.

Has the reliability of self-tests (and other tests) been altered by Omicron?

“Not as much as we’re seeing, but we’re still investigating. I’m expecting the results of that this week. But the first results show that there might not be a difference.

How long is the best time to stay in isolation after a positive self-test?

“It is advised to stay in isolation for 5 days, but I recommend staying in quarantine until a negative self-test is done.”

If you have a positive roommate who cannot self-isolate, how often should you test yourself?

“It is necessary to do this every day.”