I'd like to become a zombie again, the Great Pandemic was my favorite event ever. Is it only possible during the event, or is there an item that can be used to become infected?

as far as i know, only during the event, but you can keep the skins and wear them whenever!

I participated in the event years before the skins were implemented, do you know of any way to get them outside of the event? :O

unfortunately, you'll have to wait for the next event.

haha, darn. I remember getting infected with The Baker virus years back, I loved it! :D