Hi, know it has been a long time since these vials were released:

But how exactly do they work?

Do they have to be used during Survival and you have to wait for the "infection" to get to the end stage, before you can use another one?

Clarification on this will be most appreciated. Thank you! :)

You drink one during Survival and the infection progresses like a standard virus strain. I don't think it's possible to drink them outside of Survival anymore. Each one only has 4 stages though so you'll unlock the skin a bit faster than any of the other strains

Yep, one must wait until Survival is happening, for them to work. I just tried one and got... Oops! An error occurred: It's not Survival right now! Thank you for the clarification! Peace! :D [edit]Creeping Vial

After taking a drink, you start to feel a little strange Unlocked Hate to Burst Your Bubble! Drink an infected vial.