A newly emerged variant of the coronavirus known as "omicron" is causing widespread concern. First discovered in South Africa, it's now been detected in multiple nations, including Europe and Israel. Many nations including the U.S. are considering travel bans to try and contain the variant. Dr. Ashish Jha, dean of Brown University's School of Public Health, joins William Brangham to discuss. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders