As the novel coronavirus sweeps across the United States, it appears to be infecting and killing black Americans at a disproportionately high rate, according to a Washington Post analysis of early data from jurisdictions across the country.The emerging stark racial disparity led the surgeon general Tuesday to acknowledge in personal terms the increased risk for African Americans amid growing demands that public-health officials release more data on the race of those who are sick, hospitalized and dying of a contagion that has killed more and more people in the United States.