The World Health Organization warned Thursday the Omicron variant continues to spread rapidly worldwide. In South Africa, coronavirus infections are up by more than 250% in a week — nearly all of them Omicron cases. And the United Kingdom’s Health Security Agency said Thursday Omicron appears to be outcompeting Delta and is likely to become the dominant variant in Britain. Kate O’Brien, the head of the WHO’s Department of Immunization, warned rich countries against hoarding vaccines in response to the new variant.

Dr. Kate O’Brien: “As we head into whatever the Omicron situation is going to be, there is risk that the global supply is again going to revert to high-income countries hoarding vaccine.”