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COVID-19 rapid tests still work against new variants – researchers keep ‘testing the tests,’ and they pass

Nathaniel Hafer, UMass Chan Medical School; Anuradha Rao, Emory University, and Apurv Soni, UMass Chan Medical School, The Conversation on

Published in Health & Fitness

By September 2020, just six months after COVID-19 triggered shutdowns across the U.S., it was clear that SARS-CoV-2, the virus that causes COVID-19, had mutated from its original form.

The question quickly arose whether existing rapid antigen tests could detect newly emerging variants.

Using clinical samples obtained from diagnostic labs throughout the U.S. from 2020 to 2023, the National Institutes of Health, through its Variant Task Force, analyzed the effectiveness of more than 100 rapid antigen test kits on over 300 variants. The vast majority of the kits were able to detect new as well as prior previously known variants.

We are a team of researchers who have spent the past few years researching COVID-19 tests for their accuracy and performance. We understand why the public may still have questions about whether these tests are reliable, particularly as new variants continue to appear.

Here are answers to some of those questions:

There are two major types of tests for the detection of SARS-CoV-2.

 

The first, called a RT-PCR test, is more than 95% accurate for detecting the virus. These were the tests that most Americans were given at drive-through and walk-in testing sites early in the pandemic. The vast majority are now done at a doctor’s office or clinic, though there are some home PCR tests, which typically cost five to 10 times more than rapid antigen tests.

The other type is an antigen test, commonly known as a rapid test, with an accuracy rate of more than 80%. Most of these tests are sold over the counter at supermarkets and pharmacies.

Rapid antigen tests are relatively inexpensive, can be used without prior training and give quick results, typically within 10 or 15 minutes. One drawback is that they are less accurate than PCR tests, especially early in an infection when there is less virus present in the body.

Despite these inherent limitations, our team has demonstrated that these tests perform as well in 2024 as they did earlier in the pandemic, when different variants were circulating – even though our initial study was completed in January 2022. That’s because the virus protein detected by antigen tests has not changed much over the last two years, unlike other parts of the virus that have undergone many mutations. Another study, which tested the accuracy of rapid antigen tests from 2020 to 2022, found similar results.

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