You said "you can't know"
With COVID, you can. Pretty easily.
Re:I Got a 'Mild' Breakthrough Case
by Wowfunhappy on Sunday September 12, 2021 @05:06PM
(#28504930)
Sorry, I might not be understanding where you're going with this. I initially thought you meant "you can know you're at risk of spreading COVID, because everyone is at risk of spreading COVID."
Certainly, anyone who receives a positive PCR test for COVID should quarantine ASAP. But if you're incubating COVID, but not infectious yet, the tests will return negative. A test only tells you whether you were infectious at the time of the test, so by the time you've seen the results, the information is already outdated.
> I initially thought you meant "you can know you're at risk of spreading COVID, because everyone is at risk of spreading COVID."
No. That wouldn't be a particularly useful statement.
Dismissing the aggregate risks solely based on your own is short sighted.
Your version applies to cars too! By driving a car, you are at risk of causing a car crash!