Omicron: What Is Known And Still Unknown

What is the Omicron variant?

First identified in Botswana and South Africa, this new iteration of the coronavirus has prompted concern among scientists and public health officials because of an unusually high number of mutations that have the potential to make the virus more transmissible and less susceptible to existing vaccines.

The World Health Organization has called Omicron a “variant of concern” and on Monday warned that the global risks posed by it were “very high,” despite what officials described as a multitude of uncertainties. Cases have been identified in 20 countries so far, including Britain, Italy, Belgium and the Netherlands. On Wednesday, officials announced that Omicron had been detected in the United States — in a traveler who returned to California from South Africa.

What do we know about Omicron’s presence in the U.S.?

It’s unclear whether Omicron is already circulating in the United States. The only person to have tested positive for the variant returned to San Francisco from South Africa on Nov. 22 and tested positive on Nov. 29, according to the Centers for Disease Control and Prevention.

The individual, who was fully vaccinated, had mild symptoms and was improving, health officials said. The nation’s top infectious disease expert, Dr. Anthony S. Fauci, said that contact tracers had identified all those who had close contact with the infected individual and that so far, all of them had tested negative for the virus.