The U.S. death toll from the coronavirus-borne illness COVID-19 set a grim milestone on Tuesday when it climbed above 600,000,according to data aggregated by Johns Hopkins University. The total now stands at 600,039, the data show. The U.S. leads the world by cases, at 33.5 million, and fatalities, although the official numbers from several populous countries, including China and India, are widely held to be under-reported. U.S. cases and deaths are falling as more Americans become vaccinated. The Centers for Disease Control and Prevention’s vaccine tracker is showing that almost 145 million people, or 43.7% of its overall population, are fully inoculated.