I read somewhere, maybe it was here, that in Asian countries it was common for people to wear masks when they were not feeling well. I guess a common courtesy to not spread germs. It really does make sense to wear a mask for that purpose.
https://ew.com/celebrity/mark-ronson-robin-williams-tucking-him-bed/
When I was in junior high they brought in an impersonator of him dressed like Mork. The guy was a recovered alcoholic if I remember correctly. Williams was a great actor. Awakenings is one of my favorites.