The US is experiencing a “really unprecedented” surge in Covid cases amid the highly transmissible Omicron wave, but the peak may be only weeks away, top US infectious disease expert Anthony Fauci said on Sunday.

"We are definitely in the middle of a very severe surge and uptick in cases," Fauci said on ABC's "This Week" news programme.

Fauci said the experience of South Africa offered some hope as the Omicron strain was first detected there in late November and peaked quickly and then subsided almost as quickly.

Evidence is mounting that Omicron is milder than previous variants. The US rates of deaths and hospitalizations have been far lower in recent weeks than during previous Covid surges, he added.

"It looks, in fact, that Omicron might be less severe, at least from data that we've gathered from South Africa, from the UK and even some from preliminary data from here in the United States," Fauci said in another interview to the CNN news channel on Sunday. 

However, Fauci said there was still a danger of a surge in hospitalization due to a large number of coronavirus cases even as early data suggests the Omicron COVID-19 variant is less severe.

"The only difficulty is that if you have so many cases, even if the rate of hospitalization is lower with Omicron than it is with Delta, there is still the danger that you will have a surging of hospitalizations that might stress the healthcare system," Fauci said.

U.S. authorities registered at least 346,869 new coronavirus on Saturday, according to a Reuters tally. The U.S. death toll from COVID-19 rose by at least 377 to 828,562.

Also read: India’s Omicron count rises to 1,270, Maharashtra & Delhi worst-hit