Fauci warns some at-home tests may not detect Omicron variant as Covid cases spike across US

Dr Anthony Fauci has warned that some at-home Covid tests may not detect the new Omicron variant of the virus.

“We’re getting preliminary information that not all of the diagnostic tests will be accurate with Omicron,” Dr Fauci said in an interview with the US Chamber of Commerce on Thursday.

The infectious diseases expert, who serves as President Biden’s chief medical adviser, made the comment as he overviewed the state of the Covid-19 pandemic in the United States. The vast majority of cases in the country, he said, are still of the more common Delta variant, but the new Omicron strain – which scientists know less about, and which may be even more contagious than Delta – presents challenges as well.

Suzanne Clark, president of the Chamber of Commerce, asked Dr Fauci if rapid tests were as accurate at testing for Omicron as the more trusted PCR (polymerase chain reaction) tests.

“What about the tests we can buy in the drug store?” Ms Clark asked. “Do they also pick up Omicron?”

Dr Fauci said the answer was mixed.

“Some, and many of the commonly used ones, appear to pick up and detect Omicron quite well,” he replied. “Clearly there are some that do. We’re trying to find out those that don’t reflect an accurate result, and if we do, then to make sure that those tests are not used to diagnose Omicron.”

The new variant has alarmed officials in the US, where Omicron cases have already been identified in 38 states and the Covid positivity rate in New York City has doubled in just three days.

Officials reported 21,027 new cases in New York state on Friday, a new record for coronavirus infections, despite the state already having been the global epicentre of the pandemic during much of 2020.

“We have seen a very substantial increase in cases in the last few days,” New York mayor Bill de Blasio said at a press conference on Thursday. “It is clear that the Omicron variant is here in New York City in full force.”

But according to Dr Fauci, most of the current spike is not from Omicron, but from Delta. During Thursday’s interview, Ms Clark asked the immunologist to explain a US map in which 46 states were marked red, signifying a high level of virus transmission.

“What you see on that map there is more than 90 per cent, probably around 95 per cent Delta,” Dr Fauci answered. “So we are in the middle of a Delta resurgence.”

New Covid cases in the US were dropping throughout much of the fall. Then, in late October, they started to level off, and since early November they’ve been rising again.

“We are in a very difficult situation,” Dr Fauci said.

As always, he said, the best protection from the latest wave of the virus is to get vaccinated – and, in the case of Omicron, to get a booster shot, which has proven important to warding off the new variant.

“The very vulnerable people that are on that map of our nation are predominantly – not exclusively, but predominantly – the unvaccinated,” Dr Fauci said.