Kayleigh McEnany is a classic example. The incubation period is well established as generally being 1-14 days. In Australia a returned traveller must quarantine for 14 days. If tests were accurate on Day 1 and showed negative then there would be no need for this quarantine. But we make them quarantine for the entire 14 days because a positive test result might not show up until Day 10.
Kayleigh was a close contact of a positive case, yet used her negative test results to go about her business, potentially exposing others to the virus. Hence the “false sense of security” the tests appear to be giving those in the White House, IMO, despite these established protocols all around the world.
Here in Australia, close contacts of positive cases need to quarantine for 14 days. For this very reason.
Kayleigh McEnany infected with COVID-19