Sensitivity of a PCR from a swab sample is a funny concept

PCR itself is extremely sensitive, now it should be very specific as well

But provided that the swab captures RNA if there's any

That's the probability we need combined with PCR sens&spec (conditional on swab quality)

Similar to tuberculosis dx

Swab PCR could be used to assess contagiosity but not rule out infection, taking into account that, like TB, "viripher status" can be intermittent

The expression "swab quality" is best interpreted in the sense that even if it's a well taken sample, at the time of swabbing the patient might not be "viripher"

Just to tidy a bit my thoughts, I wrote them in this graph

But this is not how things are presented to us, because we usually encounter a given PCR test (+ or -) and we have to determine if the patient might be infected, contagious or both

The word "viripher" is just a free translation from the word "bacillipher", referring to when a patient with active tuberculosis that is also able to release bacilli both in contact and aerosol form

Thus, IF viripher status isn't time-constant, sometimes people wouldn't be contagious enough to produce a viable #aerosol

"Not the same amount, not all the time"

This might be behind heated arguments about aerosol transmission. And an interesting hypothesis to prove