I found this:
COVID-19 testing is important but has 10 to 15% rate of producing false, negative results, pathologist says
Thank you. It’s very suspicious timing. He was fb’ing on Tuesday. No indication of feeling unwell. Wednesday they say he passed from complications from the flu but the test was negative
In my opinion, there are too many cases of being negative in the beginning and turning into positive later to just be the fault of a bad test.
I really think it is more that good ole Wuhan Virus is tricky SOB and your viral load isnt high enough to test positive while the virus continues to wreck your body