'This is not our first rodeo:' Doctors discuss important tools in fight against the omicron variant

Health officials are on high alert looking for any U.S. cases of the newly identified omicron variant of COVID-19.

"It's inevitable that sooner or later it's going to spread widely because it has at least the molecular characteristics of being highly transmissible," said Dr. Anthony Fauci.

"This variant is a cause for concern, not a cause for panic," said President Biden.

The president addressed the American public on the day his administration instituted a travel ban for most non-U.S. citizens coming from several countries in Africa.

While a ban can't stop the spread, Fauci said it can buy scientists time to assess the omicron variant's threat to different people.

"There are those who have not been vaccinated. There are those who have been vaccinated and there are those who have been infected and recovered. So, the real question is how does this particular virus affect with regard to severity," he said.

While the new omicron variant of the COVID-19 virus has not yet been detected in the United States, it will "inevitably" arrive, Dr. Anthony Fauci said Sunday.

"This is not our first rodeo when it comes to variants," said USC pulmonologist Dr. Raj Dasgupta.

Despite the 50 to 80 mutations on the omicron variant's spike protein, Dasgupta said handwashing, social distancing and masking remain effective forms of prevention. He said newer treatments awaiting FDA authorization such as Merck's and Pfizer's oral antiviral therapies will be important tools to fight this and future variants.

"These are medications that are going to be attacking novel coronavirus at the RNA level and, at the protein level. So, in theory, it should avoid any of these mutations that are occurring," Dasgupta said.

Moderna and Pfizer are already working on specific boosters against the omicron variant. Scientists say they'll know in about two weeks if that's even necessary. But what experts do know about past variants is that vaccinated people do much better than those who are not.

"When you get vaccinated and boosted and your level goes way up, you're going to have some degree of protection, at least against severe disease," Fauci said.

All vaccinated adults should get COVID-19 booster shot because of omicron variant, CDC says

The WHO panel said evidence suggests there's an increased risk of reinfection, but there's no indication yet that the variant causes more severe illness.

Due to omicron variant concerns, the CDC is strengthening its booster guidelines, saying those who received an MRNA vaccine should get a booster six months after their last shot. Those who got a Johnson & Johnson vaccine should get a booster shot two months after their original shot.

A source familiar with the discussions confirmed to ABC news that Pfizer will ask the FDA to authorize boosters for those 16 to 17 years old later this week.