As some of this thread has touched on Covid tests, thought I would offer:
Just prior to Christmas, and after booking flights for three (son, d-i-l, granddaughter) from Denver to Seattle, the three visited a local pharmacy and took PCR tests (required as they were driving from Seattle across the border to Canada). The day before the flight (leaving at 7 am the next morning), the test results came back and son, g'daughter were negative while d-i-l was positive. She took a home test to confirm, which came back negative. Due to the disparity in the results and that all three were living together and in close contact, and the other two were negative, she attempted to arrange a second PCR, but only appointment was after the morning flight left, so flights cancelled.
Next morning, she took the second PCR test, results were expedited, and it came back negative. She was advised by the lab staff, that PCR tests give false positives 1 in 1000 times.
As no chance of arranging a new, inexpensive, flight to Seattle (the 24th), I bit the bullet and booked all three direct to Vancouver. Funny enough, upon arrival at YVR and while going through customs, the g'daughter (9 yrs old) was secondary'd for the purpose of a "random" Covid test (even though proof of negative tests were provided). As a result, all three took a test. All were negative.
So, the false positive result cost me $2000, compared to the $250 it was going to cost for the initial flights. Yay.
Marv