All coverage
WHO labels new Covid strain, named omicron, a 'variant of concern,' citing possible increased reinfection risk
By Robert Towey & Sam Meredith
What's known and unknown about Omicron, the coronavirus variant identified in South Africa
By Andrew Joseph
What to know about the omicron variant and subvariant BA.2
By Lindsey Bever, Joel Achenbach & Meryl Kornfield
What to know about omicron, the new COVID variant
By Michaeleen Doucleff
U.S. imposes travel ban from eight African countries over Omicron variant
By Nandita Bose & David Shepardson