Suppose I am running a several-hundred-person indoor event in the US where all attendees are required to be fully vaccinated. Suppose also that no one will come to the event if they have COVID-like symptoms. Given full vaccination and lack of symptoms, how much additional risk reduction is there from requiring people to get a negative rapid test result at the door? Also, same question, but for requiring a negative result on a PCR test <48 hours before the event.
(I did not make an effort to look into this myself because I figured someone here would already know the answer, which would be way faster than me trying to figure it out from scratch. Please someone just tell me, thank you.)