The World Health Organization is warning that the omicron variant of the coronavirus, which was first detected in South Africa, has a "very high" global risk because of the possibility that it spreads more easily and might resist vaccines and immunity in people who were infected with previous strains. On Monday, President Joe Biden said this this variant is a "cause for concern, not a cause for panic." He urged Americans to get fully vaccinated and get a booster dose if they qualify. WHO spokesperson Dr. Margaret Harris explains what more there is to learn about the severity and transmission of this new variant. And Dr. Francis Collins, director of the National Institutes of Health (NIH) discusses why vaccine hesitation on a global scale could make this next phase of the pandemic more dangerous. In participating regions, you'll also hear a local news segment that will help you make sense of what's going on in your community.Email us at considerthis@npr.org.