As the United States marked another grim milestone Thursday with more than 4,000 covid-19 deaths reported in a single day, federal disease trackers said research suggests that people without symptoms transmit more than half of all cases of the novel coronavirus.
Democracy Dies in Darkness
U.S. sets covid-19 death record as researchers point to asymptomatic cases as a major source of infections
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January 7, 2021 at 8:00 p.m. EST