Current policy seems to be no testing no virus.
Because of bureaucratic screw ups and protecting their fiefdom the US blow the month or more between the outbreak in Wuhan and the disease coming here. The CDC insisted on developing their own test and they proceeded to screw up. On top of that, the CDC insisted they would be the only body to test for COVID19. So while the South Koreans are testing 10,000 people a day, the US has tested less than 5,000 in total.