herd immunity is not a zero illness issue. It is instead, a statistical issue where if there is exposure, it doesn't sweep through the "herd" or population,
100% agreed here
The disease causing agent is simply less likely to come in contact with vulnerable people if it is surrounded by people who can't continue the transfer.
Another 100% agreement here!
Herd immunity should not count the interlopers (tourists)
I didn't want to argue about something we can't prove as easily when I just could show him that even with counting tourists as well, it would work.
Showing a clear logic mistake seemed easier than debatting over another thing to me.