1968, Hong Kong Flu raged for three years:
Just having fun and off my last engineering meeting for the week.
FWIW, the the building owner and tenants need to establish some sort of order: No more than four people on an elevator at once, if within a floor of your destination, get off and take the stairs, letting other people get on, etc.
Common sense stuff.
My local Ace does it, so can the building owners and tenants.