To actually make this a bit of a mafia game I think that all three of Shadow, Zionite, and Vaimes know who the healthy person is. I have not gotten a sense of that from Fins. For obvious reasons I can't point to why I think they know but that's my read.
I will say it's an extremely high likelihood that I'm wrong and chasing ghosts but now that I've seen what I've seen I can't unsee it.
Also this is a frustrating read to make because the last thing I want is Fins to come in and prove they know the healthy person and give it away to whoever I was wrong about so it's going to be difficult to change my mind.
Also I did have a read that everyone turbo'ing Kpaca was because they thought he missed the things I saw (and thus didn't know who the healthy person was) and were happy to go with it because if we were wrong he was a liability with the post shadow quad quoted. So I was viewing voting him as a plus. Probably shouldn't weight it as heavily as I was though.
Putting the time travellers in the quarantine with us. Pretty sure that's been the plot of like five different Doctor Who episodes. Usually with the virus turning out to be an evil plot or rogue nanobot.