You get the option to use the cure on the boy or keep it for yourself. If you use it on the boy you keep a permanent -10 hp perk from the disease.

Can you avoid contracting the disease if you never get hit by any of the infected molerats by sneaking around or using followers for combat?

  • 2
    Wait... I contracted a disease? Don't recall noticing that, and I know I took a few hits in there somewhere. I was beginning to wonder why there was even an option to keep the cure.
    – Iszi
    Commented Nov 16, 2015 at 20:58
  • 1
    Check your perk list or status effects, you have a -10 max HP.
    – SkyHiRider
    Commented Nov 16, 2015 at 21:30
  • @Iszi the option is always there, even if you don't contract the disease
    – Dallium
    Commented Nov 18, 2015 at 19:53
  • @Dallium Thanks for the tip. I rebooted my game the other night for unrelated reasons anyway. So I'll just try to watch out and not get bit, I guess.
    – Iszi
    Commented Nov 18, 2015 at 19:59
  • 9
    So that's where I got sick.
    – DCShannon
    Commented Nov 25, 2015 at 17:52

8 Answers 8


You will contract the disease if:

  • You get hit by a mole rat
  • Your companion gets hit by a mole rat
  • The protectron you can activate via terminal gets hit by a mole rat

Long story short, don't use a companion (or have them stay by the entrance), don't activate the protectron and Don't Get Hit. I was able to get through without catching the disease by abusing VATS and quick saves.

Note that the mole rats can be hit by grenades even while underground. If you get ambushed and have to reload, toss a Molotov Cocktail at the ground where the Mole Rat would appear and roast it early.

Also note that burrowed mole rats Will trigger mines. I tried to use mines on top of where they would spawn and blew myself up.

  • I can confirm the protectron getting hit causes you to get hit. I played the mission 30 sec at a time, quicksaving each time. Somehow I kept getting the disease even when never being detected. Eventually I noticed that it always coincided with the protectron being hit. After killing the protectron myself, I made it through the mission without being infected (I never play with a companion, so I can't confirm or deny that part, but it seems plausible).
    – Svj0hn
    Commented Dec 8, 2015 at 6:46
  • I've also done this now, and can confirm I got the disease from both the Protectron and my companion. Stupid, but true.
    – DCShannon
    Commented Dec 8, 2015 at 21:02
  • Can confirm that you'll get the disease even without being hit yourself, and even with Power Armor or the Hazmat suit on. Haven't tested without a companion, or the Protectron, so it's possible that's what was compromising me.
    – Iszi
    Commented Dec 9, 2015 at 21:01
  • This is fixed in the Unofficial Fallout 4 Patch, which is available on both PC and consoles. afkmods.iguanadons.net/…
    – DCShannon
    Commented Sep 20, 2016 at 20:41
  • It seems like the mole rat can sometimes be shot at even when burrowed. I can sometimes VAT target them and kill them. I'm also using an explosive weapon so that's probably why.
    – Nelson
    Commented Sep 29, 2016 at 8:04

Here is some information about doing this on survival mode.

General tips:

  • Just before you get to the ceiling turrets there is a bed you can use for saving. I was not able to save in any beds past this point.
  • The secret part of the vault has some great loot. I brought all the good stuff back to the save room and stashed it in one of the dressers. When you are done with the quest, you can make a few quick trips back through the reactor room to get your loot.
  • There is a drinking fountain in the hallway just past the save room if you get thirsty.
  • Bring a lot of frag mines, frag grenades, and/or molotovs. It makes everything a lot easier.
  • Bring a fast-shooting weapon with a reasonable clip that can 1-shot-kill a mole rat. I used a combat shotgun.
  • I did this on survival at about level 30. I did not have a very stealthy character. Your mileage may vary.


  1. There wasn't anything in the first section for me. Just move on through until you get to a room with a terminal and a bed. This is the save room.
  2. Just outside of the save room, there are two ceiling turrets and a protectron. Kill them and save.
  3. Keep going until you get to a staircase down to a cafeteria. Run down the stairs and hide in the cafeteria. You don't need to sneak since the turret won't activate very quickly. Hang out until the coast is clear, pop out and kill it. Go back to the bed and save.
  4. (optional) Activate and kill the protectron. If you throw mines down at the bottom of the stairs, it'll blow itself up. The protectron was a legendary for me and I wanted its loot. Go back and save.
  5. Go down the stairs to enter a dirt area. There are some mole rats in here. Toss down a mine or two in the entrance doorway and in the passage into the room. There is an underground mole rat in the far left corner as you enter into the main chamber. It's kind of a cul-de-sac. Toss a grenade back there and race back out of the room to where protectron in step 4 is located. Try to not be stealthy so they come after you. In my game, the grenade killed the mole rat in the back and the others popped out of the dirt just before the entrance, blowing themselves up on the mines. I took out the last one or two. Save.
  6. The dirt room ground floor should now be largely cleared of rats. Sneak back in and go up the stairs. Toss a mine on the stairs behind you in case anything pops out. Ditto on the next stairs that lead up to the door.
  7. Toss a mine down in the doorway, and a few more down the hallway near where the room opens up. Find a good corner to nest in and toss a few grenades around to alert the rats here. Be careful to not detonate your own mines, though. Most of the rats will hit your mines. Some came from behind and some from the room in front of me. I only had to shoot one or two. Go back and save.
  8. At this point, I ran around non-stealthy in the areas I'd cleared to make sure I'd killed everything.
  9. Sneak back to door that leads to the stairs down. Open it up and lay a few mines around the stairs and in the room. Toss a grenade into the downstairs room to alert the rats and run back behind your mines. Most of the rats will die on the mines. Save.
  10. Head downstairs to the dirt area. There will probably still be a rat or two down here. Toss a grenade or three around to kill them or bring them to the surface so you can kill them. When everything is dead, save.
  11. In the next area, there will be rat cages/cells with the doors open. Rats will come out of them. You can either throw grenades into the cages or drop some mines, rile up the rats, and let them blow themselves up. I think my game had three rats here. Save.
  12. You'll enter an elevated atrium area. The path to the right is blocked by crates and there will be an expert terminal you can open to bypass the rats and get to Curie. I wanted the loot, so I went left, where there a lot of mole rats. These seemed more powerful than the others and took a few hits to bring down. Again, grenades into the cages or leaving a mine trail will work well. In my game, one of the rats was glowing and had a lot of hit points. I used a critical to take him out.
  13. At this point, all the rats should be dead so you don't need to save. You can just go meet Curie and finish the quest.

I checked and found that you contract the disease even if you don't get hit, so long as someone in your party gets hits. I know for a fact I wasn't damaged (hid on top of a box where they couldn't reach me) yet each time I still contracted the disease. Long story short it's worth the -10 hit points for what you'll get in return (if you give the cure to Austin).

  • 1
    If you sneak kill all enemies then you should be able to not get infected
    – SkyHiRider
    Commented Dec 8, 2015 at 11:20
  • @SkyHiRider Perhaps, so long as your party members aren't stupid and overly aggressive.
    – Iszi
    Commented Dec 9, 2015 at 20:59
  • Or if you dismiss followers ...
    – SkyHiRider
    Commented Dec 9, 2015 at 21:15

If you go in solo, and don't get hit, you won't contact the virus. An easy solution is to switch the difficulty down to very easy, just for this mission. Limits there numbers and the odds of being infected. Abuse vats and quick saves, check your status after every confrontation. Make sure you grab the bobble head when you're down there! You can contract the virus post mission if you go back down there and get bit


I did this last night, I can confirm that you need to do the following: 1. Not get hit. There is a very small chance that if you do get hit, you will be fine, but most of the time you will contract the disease. 2. Your companion getting hit will contract the disease for you. Its easier to just tell your companion to wait in the normal vault 81 until you get back. 3. The protectron you can activate can contract the disease for you, so that also is generally not worth taking along because of this.

In the end, it took me a lot of saving and reloading to do this correctly, but by the end I cleared the whole place, didn't get infected, and got to save the kid/obtain Curie as a companion. Its worth taking the time to do this right imo, so just be careful and don't bring any help, as they will likely contract the disease for you.


Just sharing my own experience here. After realizing that hits to companions and allies infect you**, I went in on my own, and had a hell of a time keeping the little buggers off me. After a failed attempt to plant a mine at one spot and watching it blow up in my face immediately, I realized the mole rats don't exactly spawn in when you get close, they are there already, just under the surface and not actively hostile until they detect you.

I happened to have a rifle with the explosive effect, so the next run through, I just peppered every pile of dirt with a few shots. It worked like a charm, killing most of them before they could finish bursting out of the ground. If you don't have a weapon with that effect, it should still work if you have enough explosives to lob around. Turned an extremely frustrating quest into a walk.

** (Side note: really, Bethesda? That's some extra sharp cheddar right there.)


You can if you dont get hit sneak around power armor or compianions but companion will get it even if not human

  • This is a very unclear answer, not least due to a lack of punctuation. Also, what's power armor got to do with it? I contracted the disease after getting hit with power armor on in my attempts.
    – Iszi
    Commented Dec 9, 2015 at 20:58

if you can kill every molerat without getting bitten you won't get the disease

  • Tried this myself and found that I was contracting the disease even without getting hit.
    – Iszi
    Commented Dec 9, 2015 at 20:58

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