(Jae C. Hong | AP file photo) Romelia Navarro, 64, weeps on July 31, 2020, while hugging her husband, Antonio, in his final moments in a COVID-19 unit at St. Jude Medical Center in Fullerton, Calif. The U.S. death toll from COVID-19 has topped 500,000 — a number so staggering that a top health researchers says it is hard to imagine an American who hasn't lost a relative or doesn't know someone who died.