Dr. Anthony Fauci
Dr. Anthony FauciReuters

Dr. Anthony Fauci, the top US infectious disease expert, said on Tuesday that it is too early to know whether the Omicron variant of COVID-19 will lead to severe disease, adding that preliminary information from South Africa indicates it does not result in unusual symptoms.

Fauci said there were 226 confirmed cases of the variant in 20 countries as of Tuesday morning but Omicron had not been detected yet in the United States.

"It is very difficult to know whether or not this particular variant is going to result in severe disease," Fauci told reporters in a briefing, according to Reuters. "Although some preliminary information from South Africa suggests no unusual symptoms ... we do not know, and it is too early to tell."

"We are hoping, and I think with good reason, to feel good that there will be some degree of protection" against the variant from the vaccines, Fauci said. "If you're unvaccinated, get vaccinated. And if you're vaccinated, get boosted."

Asked on Tuesday if the United States was doing enough to vaccinate the rest of the world, Fauci noted the United States was doing more than other nations.

"'Enough' is a tough word. Are we doing a lot? We are doing an awful lot," he said, according to Reuters.

President Joe Biden said on Monday that the newly discovered Omicron variant “is a cause for concern, not a cause for panic.”

“We have the best vaccine in the world, the best medicines, the best scientists, and we're learning more every single day. And we'll fight this variant with scientific and knowledgeable actions and speed, not chaos and confusion. We have more tools today to fight the variant than we've ever had before,” he added.

Later on Monday, the US Centers for Disease Control and Prevention (CDC) issued a new guidance recommending booster shots for all vaccinated people 18 and older.

The guidance, which previously said adults “may” get boosters, now says they “should” get a third dose of the Moderna or Pfizer shot six months after their second dose. The same recommendation applies to those who received the single-shot Johnson & Johnson vaccine but after only two months.