Vault 81 & the Incurable Mole rat disease
Mole rat disease is a potentially permanent effect the player character obtains if bitten by an infected mole rat in Vault 81 during the quest Hole in the Wall. The effect is -10 Max HP. So where health is concerned, the disease permanently lowers the Sole Survivor’s Level by 1. During the quest, the Sole Survivor will obtain the only dose of the cure available. If the player character has contracted the disease then there is a choice to either save the life of Austin Engill, a young boy who was bitten by an infected mole rat himself, or use the cure on themselves. If the Sole Survivor cures Austin of mole rat disease, they will gain the favor of the vault as well as a room to stay in and access to all of the publicly-placed items in the vault, even those in the Depot.
VIA https://fallout.fandom.com/wiki
I’m playing a second playthrough of Fallout 4 and I get to vault 81, there are a few quests in this vault. One of them involved getting a girl named Erin Combes, runaway cat back. I come back into the vault after finding the cat and sending it home to find out one of the other kids named Austin gets bitten by a molerat, when he was snooping around in an area he shouldn’t have been in.
He ended up contracting this disease that only seems to come from molerats in the area he shouldn’t have been in.
I didn’t know this until after leaving finishing the quest, but I had got bitten a few times and contracted the disease myself. For me it only reduced my HP by 10 points, I’d find out that this is permanent. I can’t get rid of it unless I use a mod. Mods take away your ability to platinum the game.
I had to go back to the earliest save point which was a day (or hours) earlier, replay the whole vault and that specific mission just to avoid getting the disease. Which wasn’t easy. I had to quick save & reload the save every time I progressed because you could catch the disease easily.
I’ve been playing Fallout games since Fallout 3, at no point in those games do I remember a time where you could catch a disease that wasn’t curable. Not even the Elder Scroll games (which I’ll admit I’ve only played Oblivion & Skyrim). You could recover from diseases in those games.