A view of the Centers for Disease Control headquarters in Atlanta, Georgia on April 23. Starting Monday in the UK, passengers must have a negative Covid-19 test within three days of boarding a flight to the United States. "Today, President Trump is taking another step to protect the health of the American people," the statement said. But according to researchers on the CDC's Covid-19 response team, testing three days before a flight might not accomplish very much -- only reducing the risk of spreading the virus by 5-9%. The CDC's order acknowledges that "testing does not eliminate all risk," but when combined with other measures like self-monitoring for symptoms, masks and distancing, "it can make travel safer."

Source: CNN December 26, 2020 05:03 UTC