The World Health Organization chief on Wednesday said a nearly 90% drop in recent COVID-19 deaths globally compared to nine months ago provides "cause for optimism," but still urged vigilance against the pandemic as variants continue to crop up. Director-General Tedros Adhanom Ghebreyesus said that last week just over 9,400 deaths linked to the coronavirus were reported to the WHO. In February of this year, he said, weekly deaths had topped 75,000 globally. "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,"...