Can Rapid Tests Detect New COVID Variants Like BA.2.86?

Recently, Omicron subvariants like EG.5, FL.1.5.1, and the highly-mutated BA.2.86 have been causing alarm and accounting for an increasing number of COVID-19 infections. Although they have many different mutations from known variants, experts say rapid antigen tests would have no problem detecting them. Here’s what you need to know. 

Existing Rapid Tests Should Detect Newer Variants

Gonazalo Bearman, MD, chair of the division of infectious diseases at Virginia Commonwealth University Health, told Verywell that the COVID-19 rapid tests are “no more or no less effective with the current strains.”

Most rapid tests are “antigen” tests, which work by detecting proteins on the surface of the SARS-CoV-2 virus separate from the spike protein involved in viral mutations. These surface proteins have not sufficiently mutated to the point of being undetectable, by rapid tests, he added.

According to a risk assessment summary from the Centers for Disease Control and Prevention (CDC), existing tests used to detect COVID-19 remain effective with BA.2.86, which has over 35 amino acid mutations compared to XBB.1.5. The agency says that the anticipated impact of the variant on molecular (including PCR) and antigen-based testing is low.

Which Factors Impact Test Accuracy?

Susan Kline, MD, director of the division of infectious diseases and international medicine at the University of Minnesota, told Verywell that several factors can affect how well COVID-19 rapid tests detect new variants. The sampling process, amount of virus present, test sensitivity and expiration, and “any major mutations that cause large changes in the virus proteins or antigens” should all be considered, she added.

If you perform a nasal swab incorrectly, the test might not be able to accurately detect whether you have COVID-19 or not. In addition, rapid tests generally have low detection sensitivity for low viral load samples, which might miss presymptomatic and asymptomatic cases of COVID-19 during the incubation phase. 

Can Rapid Tests Go Bad?

It’s necessary to store test kits based on the temperature and storage recommendations indicated by the manufacturer. Keeping tests in the back of a hot car or inside the refrigerator may affect the accuracy of the test.

Expired tests may not provide accurate results either. You can tell if a rapid test is expired by checking the box for the expiration date.

Some tests do have shelf life extensions granted by the Food and Drug Administration (FDA), meaning they last longer than indicated on the packaging. For instance, the BinaxNOW and Flowflex tests were granted 15- to 22-month and 21- to 24-month shelf life extensions, respectively, earlier this year.

You can visit the FDA website to check the list of manufacturers and specific lot numbers that were granted the shelf life extensions.

Will COVID Tests Get an Update?

It’s not yet certain whether current rapid tests for COVID-19 will need tweaking to detect newer variants more effectively, Kline said.

Test manufacturers, government agencies, and researchers “need to run tests to further verify the sensitivity of the rapid antigen tests in patients with the newer strains of the virus infection,” she added.

Vaccines require greater specificity and are often updated to match the circulating strains of the virus because they serve to elicit an immune response. But rapid antigen tests generally “do not require the tweaking that is required of vaccines,” Bearman said.

The FDA continues to evaluate the impact of SARS-CoV-2 viral mutations on COVID-19 diagnostic tests and will update their guidance when new information becomes available. Just like before, if you get a negative test result, take another test after 48 hours to ensure that it was not a false negative.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.