"If you've already had diarrhea, you probably won't v*"

[k10]

Basically if you have diarreah for say 8 hours, it means the worst part (start) of the virus has taken hold and from then on your body mounts a defence and you start slowly feeling better. therefore if you brain hasn't engaged it vomiting mechanism by then, it is very unlikely it will, as the virus is in a decline and therefore your immune system does not need to start the vomiting cycle to remove the virus. Hope that makes sense.

This is the kind of answer I was looking for. Thanks!