Omicron may escape RT-PCR as US FDA says tests 'less sensitive' in detecting new variant

The US Food and Drug Administration (FDA) on Tuesday said that on the basis of some of the preliminary research it has been found that the COVID-19 Rapid Antigen Tests may be less sensitive in detecting the highly mutated Omicron variant. The National Institutes of Health (NIH) and FDA in collaboration conducted research about how well the antigen tests work to detect the new B.1.1.529 variant. In its analysis, the agency wrote that the antigen tests “do detect the omicron variant but may have reduced sensitivity,” according to NPR. This implies that there is an increased risk that a COVID-19 infection might be missed from the testing, a scenario known as the ”false negative.” Although the FDA didn't specify the brands of tests that it used in the study.

"The FDA continues to authorise the use of these tests as directed in the authorized labelling and individuals should continue to use them in accordance with the instructions included with the tests," the agency said in a statement on Dec. 28. "Antigen tests are generally less sensitive and less likely to pick up very early infections compared to molecular tests.”

Follow-up testing recommended

Furthermore, a senior researcher at the Johns Hopkins Center for Health Security, Gigi Gronvall, stressed that the new finding emphasises on the challenge posed by the evolving nature of the virus and the new variant. In a phone interview to NPR, the former also stated that with every new variant, for instance, B.1.1.529, and previously Delta, the health bodies have to ensure that the tests work as it is the effective method for contact tracing and isolation.

She then went on to add “it looks like the tests work for this. But they're not picking up infections as early as previous versions.” “So if you feel any symptoms but test negative, it's not a get-out-of-jail-free card. You may need to test again and hold off a little bit on assuming that you're negative,” she stated.

After its analysis, the US FDA has now encouraged follow-up testing in order to effectively test and identify the B.1.1.529 strain. “If a person tests positive with an antigen test, they should self-isolate and seek follow-up care with a health care provider to determine the next steps,” the agency said in the statement.