Dr. Anthony Fauci said Sunday that the United States is experiencing “almost a vertical increase” in COVID-19 cases as Omicron sweeps the nation, according to Medical Xpress.

Dr. Fauci, the nation’s top infectious disease expert and pandemic advisor, said the surge may be only weeks away.

Fauci said on ABC’s This Week, “We are definitely in the middle of a very severe surge and uptick in cases,” adding that the soaring infection rate is “really unprecedented.”

On Friday, the United States reported more than 440,000 new cases of COVID-19, with the Omicron strain sweeping around the world.

Citing the experience of South Africa, where Omicron was first identified in late November, Dr. Fauci said it peaked quickly and then subsided almost as quickly, offering some hope.

He explained that there is growing evidence of Omicron being milder than previous strains. The number of hospitalizations and deaths in the United States has been far lower in recent weeks than during previous surges.

In the United States, children are set to return to school today following the year-end break. Dr. Fauci and US Education Secretary Miguel Cardona said they thought in-person instruction could be conducted safely if proper precautions are taken.

Dr. Fauci, who is the director of the National Institute of Allergy and Infectious Diseases (NIAID), urged parents to make sure their kids are vaccinated, wear masks, and get tested if need be.

He said, “I think all those things put together, it’s safe enough to get those kids back to school, balanced against the deleterious effects of keeping them out.”

Meanwhile, Cardona said the return to the classroom would be challenging, but necessary.

He told Fox News Sunday, “I do think there will be bumps in the road, especially tomorrow,” with large numbers of teachers and staff calling in sick. “So we are going to roll up our sleeves, all hands on deck, let’s keep our children in the classroom. That should be our default thinking.”

Eric Adams, New York City’s new mayor, said there was little choice but for children to return safely to school.

He said on ABC, “We’ve lost almost two years of education. We can’t do it again… The safest place for children is inside a school.” Adams faces a great challenge of pulling NYC out of the pandemic, as the city is grappling with record numbers of cases, predominantly driven by Omicron.