[usrn]

You're not even guaranteed to get infected (I still haven't been.) So you need to apply that prior as well.

[nradov]

The virus will be around forever so unless you live in a sterile bubble everyone will be occasionally exposed. So infection isn't 100% guaranteed, but it's close.

https://www.medpagetoday.com/opinion/vinay-prasad/94646

How do you know you haven't been infected? Asymptomatic cases are common, and most people aren't getting frequent tests.