Scientists keep an eye on "stealth" Omicron variant BA.2

Scientists and health officials around the world are keeping their eyes on a version of the Omicron variant that has been found in at least 40 countries, including the United States.

This version of the coronavirus, which scientists call BA.2, is widely considered stealthier than the original version of Omicron because particular genetic traits make it somewhat harder to detect. Some scientists worry it could also be more contagious.

But they say there's a lot they still don't know about it, including whether it evades vaccines better or causes more severe disease.