Everything you need to know about rapid COVID-19 tests

A sign for COVID-19 testing
People who arrived on international flights wait to be tested on the first day of a new rapid COVID-19 testing site for arriving international passengers at Los Angeles International Airport earlier this month.
Mario Tama | Getty Images file

Minnesota remains among the top five states in new COVID-19 infections as the delta variant of the coronavirus continues to spread, and admissions due to the disease are adding to the crush in Minnesota hospitals. In the UK, researchers are investigating whether the omicron variant could overtake delta.

And all this is happening just ahead of the holidays, when many in-person gatherings are likely to take place. Experts such as Michael Osterholm from the University of Minnesota have suggested that Minnesotans use rapid COVID-19 tests before gatherings as one of several safety measures to prevent the spread of the virus.

But rapid tests have been hard to find, and they’re often expensive if you can get one. Why? Matt Binnicker, director of clinical virology at Mayo Clinic, joined host Cathy Wurzer with more.

Use the audio player above to listen to the full conversation or read an edited transcript below.

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What are the different kinds of tests?

First, what are the differences between the various kinds of COVID-19 tests?

Antigen tests are the tests frequently referred to as rapid or at-home tests. These tests look for a protein from the coronavirus. Those tests are not as sensitive as PCR tests, so it’s possible for someone who is infected with the coronavirus to test negative on an antigen test, especially soon after infection. But on the plus side, antigen tests are very convenient and quick to produce results.

PCR tests are considered the “gold standard” of COVID-19 testing because they provide the highest level of confidence. These tests look for RNA from the coronavirus.

PCR tests are extremely sensitive and can even diagnose patients who do not contain high amounts of the virus. The drawback of these tests? They’re usually analyzed in a laboratory, so it can take a day or two, or even several days, to get your results.

When should I get a rapid test?

Binnicker told Wurzer that it can be challenging to figure out when to use a rapid test, especially if you’re asymptomatic. Moreover, if you test negative for COVID-19 on a rapid test, that doesn’t mean you have a free pass to interact with people without other precautions.

However, Binnicker said that rapid tests can serve as a valuable component of a multi-faceted risk-mitigation strategy before gatherings like holiday get-togethers — along with vaccination, masking, distancing and other commonly recommended precautions.

Is the U.S. lagging behind other countries in the use of rapid tests?

Some countries like the UK and Germany have provided free at-home COVID-19 tests to their citizens. Why hasn’t the U.S. followed suit? Why are rapid tests so scarce and expensive here?

Binnicker pointed to high regulatory barriers to new tests in the U.S. These barriers mean we have higher quality tests, Binnicker said, but they also mean that the costs of developing and manufacturing tests are higher, which can slow their arrival to market and make them more expensive for consumers.

He added that high demand for tests, supply chain issues and the need for manufacturers to produce other tests — like influenza tests — have also limited access to rapid tests in the U.S.

Binnicker said that scientists are still learning about which situations rapid tests are most useful in, and he reiterated that testing is only one component of the fight against COVID-19, not a silver bullet.

We want to hear from you

What other questions do you have about rapid tests or COVID-19 testing in general? Email your questions to minnesotanow@mpr.org, or tweet them at @CathyWurzer.

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