COVID-19 deaths have fallen significantly over the last nine months, but the world must remain vigilant as new subvariants spread, the World Health Organization’s top official said Nov. 9.

Last week, about 9,400 deaths were reported globally, down nearly 90 percent from February, when the weekly death toll topped 75,000, according to WHO Director-General Tedros Adhanom Ghebreyesus, PhD.

“We have come a long way, and this is definitely cause for optimism, but we continue to call on all governments, communities and individuals to remain vigilant,” he said. “Almost 10,000 deaths a week is 10,000 too many, for a disease that can be prevented and treated.”

Dr. Tedros’ call for vigilance comes as omicron subvariants BQ.1 and BQ.1.1 — dubbed ‘escape variants’ for their immune evasiveness — account for more than a third of COVID-19 cases in the U.S.