Do you think the children in Hogwarts are home schooling? I'm just reading about how they cram all the first years into a room before they put on the sorting hat. Do you think first year traditions will change? No train, no boats no hat?
They have a sanatorium at Hogwarts although it seems to be mainly populated with people who have faced mortal danger or broken bones, they definitely do not have as many regular sick people as Mallory Towers. Although St Mungos specialises in tropical medicine.
So ianbu, of course the Wizarding world would be affected by a world wide virus
Iabu Wizarding magic is beyond the realms of us muggles so they already have a cure.