Passengers without proof of a negative test will not be allowed to board flights to America
CDC: Travelers From the U.K. Must Have Negative COVID-19 Test
If a traveler opts not to take a test, the airline must deny boarding the passenger
CDC Recommends Three COVID-19 Tests for Americans Traveling Abroad
Tests recommended one to three days before the flight, three to five days after the flight, and one to three days before returning