Fauci says omicron Covid variant has already been found in 20 countries, but not yet in the U.S.

White House chief medical advisor Dr. Anthony Fauci said Tuesday that 226 cases of the highly mutated omicron Covid-19 variant have been detected across 20 countries so far, but U.S. officials haven’t confirmed a case in the states yet.

The variant, which first emerged in South Africa about a week ago, has more than 30 mutations to the spike protein alone. That’s the key part of the virus that allows it to bind to human cells and infect the body. It also makes scientists worry that it could be far more infectious than the already highly contagious delta variant that’s caused a surge in cases across globe in recent months.

“This mutational profile is very different from other variants of interest and concern, and although some mutations are also found in delta, this is not delta,” Fauci told reporters on a White House Covid-19 task force briefing. “These mutations have been associated with increase transmissibility and immune evasion.”

There are several other mutations to the virus that scientists haven’t seen before and don’t know how they will change how the virus behaves or spreads, he said.

U.S. officials are stepping up surveillance of international travelers at airports and holding regular, even daily, calls with state and local health officials, lab directors, state epidemiologists and others, looking for omicron cases, said Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention.

The nation also has stepped up genomic sequencing of Covid cases in recent months, sequencing about 80,000 samples per week, up from about 8,000 a week earlier this year, Walensky said at the briefing. The delta variant remains the predominant strain in the U.S., accounting for about 99.9% of all cases sequenced across the country, she said.

“To be crystal clear, we have far more tools to fight the variant today than we had at this time last year,” Walensky said.

Fauci said it’s too early to tell whether omicron will be more deadly or mild than the delta variant. He noted that reports of more mild symptoms in South Africa were based on a small number of cases and occurred in younger and healthier patients who would typically have milder Covid. People in the U.S. and Europe tend to be older and less healthy than South Africa’s population, Moderna CEO Stephane Bancel said in an interview on CNBC on Monday.

“It is very difficult to know whether or not this particular variant is going to result in severe disease,” Fauci said. “Although some preliminary information from South Africa, suggests, no unusual symptoms associated with variant, we do not know and it is too early to tell.”

The officials reiterated their push to increase vaccinations, saying the best tool to protect yourself against the variant is to get vaccinated, boosted and continue to wear masks and avoid crowds.

“How do we address omicron? We’ve said it over and over again, and it deserves repeating, if you’re not vaccinated, get vaccinated. Get boosted if you are vaccinated. Continue to use the mitigation methods namely masks avoiding crowds and poorly ventilated spaces,” Fauci said.

Walensky said the CDC’s definition of “fully vaccinated” hasn’t changed. It’s still two weeks after the second shot of Moderna or Pfizer’s vaccines or one of Johnson & Johnson’s. But she said the more the virus mutates, the greater the need to bolster immunity. “As that science evolves, we will look at whether we need to update our definition of fully vaccinated,” she said.