[cypherpunks01]

It does move down the respiratory tract, but nasal epithelial tissue can still contain/produce the virus for awhile even after it "moves". For me, I was able to physically feel the inflammation move down from my throat to lungs to abdomen, but that was 5 weeks ago, and I just tested positive on a deep nose swab rtPCR given yesterday. A lot of people are testing positive for surprisingly long time.

I wouldn't be surprised if a light nasal swab like being discussed here doesn't pick up anything post-symptoms, whereas PCR with the deep nasal swab may still be detectable for a longer time after primary symptoms have faded.