Are over-the-counter COVID-19 tests reliable?

Data and Metrics Testing and Contact Tracing

Over-the-counter COVID-19 tests are now available in the United States. For 30 to 50 bucks, you get an answer in 25-45 minutes in the comfort of your home, much like the free rapid antigen tests used in the UK.

Can you trust the results? It depends.

Dr. Chana Davis from Fueled by Science gives us the tl;dr on OTC self-tests:

First things first. If your odds of truly having COVID-19 are high (e.g. a known COVID-19 exposure or multiple symptoms), head to the lab if at all possible. Lab tests miss fewer cases, especially when viral load is low.

Self tests can be useful when your odds of having COVID-19 are low but you want peace of mind. Most likely, you’ll get the negative result you were hoping for. Phew! There is also a small chance you’ll get a false positive and be told you have COVID-19 when you don’t (~1 in 50 self tests). Occasionally, you’ll catch a sneaky case.

🧪 If you get a positive COVID-19 self test, don’t panic. There is a good chance it’s a false positive (oops!). Try repeating the test. It’s wise to also get a lab test just to be sure.

❓Why are positive results unreliable? When COVID-19 rates are low, false positives (1 in 50) far outnumber true positives (under 1 in 1000 among Americans without exposure or symptoms).

False positive tests can stem from test error or user error, like waiting too long.

😊 If you get a negative self test you can relax. Unless your pre-test chances of having COVID-19 were very high, negative tests are right 99% of the time.

➡️ Check out the graphics to see how reliable positive and negative test are, and how the answer changes depending on your odds of having COVID-19 before testing.

🌟 The Bottom Line: Self tests can be useful when used appropriately, with eyes wide open. In low risk settings, they often deliver peace of mind. In high risk settings, lab tests are a better bet.

Note: There is much more nuance to testing, from variation between tests and users, to repeat testing. This only covers the basics!

🗣️ How do you feel about at-home COVID-19 tests? Let us know!

🇨🇦 P.S. At-home COVID-19 tests are not yet available in Canada. If they were, I would consider testing my (unvaccinated) kids before an extended vacation with another family.


New Rapid Home Test for COVID-19

Why are there so many tests for COVID-19? How do I know which one is best for me?

MIT Review of Three Over-The-Counter Tests

Potential for False Positive Results with Antigen Tests for Rapid Detection of SARS-CoV-2 – Letter to Clinical Laboratory Staff and Health Care Providers


Link to Original FB Post