Omicron: What Is Known — and Still Unknown

Intense research into the new coronavirus variant first identified in southern Africa has just begun. World leaders have urged people not to panic — and to get vaccinated, if they can.

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. Although Omicron has not yet been detected in the United States, experts say it is only a matter of time before the variant shows up.

Omicron’s discovery has prompted considerable panic across the globe, with a number of countries banning flights from southern Africa, or — like Israel, Japan and Morocco — barring entry of foreign travelers altogether.