The FDA previously tested the accuracy of the tests using samples of dead Omicron virus, and found they were just as effective.

But now lab tests using live samples of the virus have raised fresh doubts about their accuracy.

‘Early data suggests that antigen tests do detect the Omicron variant but may have reduced sensitivity,’ they said.

However, the FDA is still advising people to use lateral flow tests, saying the findings are still at an early stage.