COVID-19 cases continue to surge in the United States, Europe and South Africa, where the fast-spreading Omicron variant was first detected. On Tuesday, South Africa’s largest private health insurer reported Omicron appears to be substantially more contagious than even the Delta variant — and reduces the effectiveness of existing vaccines, though people who are fully vaccinated are largely still protected against severe disease.

In Britain, Health Secretary Sajid Javid warned the Omicron coronavirus variant is spreading rapidly across the U.K. and appears poised to overtake Delta as the dominant variant.

Sajid Javid: “First of all, it’s spreading at a phenomenal rate. The number of infections is doubling every two or three days. There’s going to be a tidal wave of infection. The second thing that we’ve learned in the last week is that two doses of the vaccine are not enough to protect you, but three doses, a booster shot, is, will be hugely effective in protecting you against symptomatic infection.”

Prime Minister Boris Johnson on Monday announced the world’s first known death linked to the Omicron variant. Last week, Johnson reversed his long-standing opposition to public health measures and ordered new restrictions, including mask mandates and proof of vaccination, while urging people to work from home.