The Centers for Disease Control and Prevention late Monday raised its travel advisory for South Korea to its highest level after the number of confirmed coronavirus cases in the country surged past 800. The Level 3 warning means Americans should avoid all nonessential travel to South Korea, which has the highest concentration of coronavirus infections outside China. South Korean officials say 893 people have tested positive for the novel virus. The CDC’s Level 3 travel warning means Americans should avoid all nonessential travel to South Korea, which has the highest concentration of coronavirus infections outside China. South Korea now has...