Coronavirus live updates: As US death toll approaches 400K, new variants threaten to add to struggle; Americans' trust in vaccines grows John Bacon, Jorge L. Ortiz and Doyle Rice, USA TODAY How viruses like COVID-19 mutate, and how they impact vaccine development Replay Video UP NEXT The U.S. on Monday stood on the brink of 400,000 reported coronavirus deaths, almost double the total of the next most severely hit nation and still mourning more than 20,000 deaths per week. The U.S. has added almost 4 million new infections this month, and the emergence of new variants only figures to add to that total.