So I finished the game a few days ago and really loved it. But I was wondering if it was ever explained why Ellie was immune to the virus. My first assumption was that it had to do something with her being born after the virus had already spread, but then you meet Sam who was also born into this mess and he was obviously not immune.

Can anyone shed some light on this?

I do not believe they ever explained why she is immune while others are not. In fact, the point of the final medical scene was to figure out how she was immune and find a way to replicate that success with others. So, no, it was not conclusively explained.

They do appear to suggest that it might be an antibody resistance to the infection, but until they chopped her up, they apparently had no way of knowing for sure why she had an immunity while others did not.

An explanation wasn't really necessary for the story, but I suppose they could explain it in a sequel if they were so inclined.

@truthtellah: There's a little bit of medical mumbo jumbo in end game audiologs about how her cerebrum is blocking the virus or something like that. It's not really important in the grand scheme of things, all that the player really needs to know is that she is special.

Yeah, the infection focuses on the brain, and they found that while her brain had the infection, it wasn't able to grow on her brain. I believe they theorized it was due to some kind of antibodies fighting off the infection, but I think that was just a theory. They said they had to remove the brain to figure out exactly how it was fighting the infection. Thus, the climactic scene.

Wasn't the whole point that she wasn't actually immune, the infection had just mutated? She was still infected, but it was benign growth. So they needed to remove the growth (which grew in her brain) to study it. It didn't even necessarily need to be something special about Ellie, it could've just as well been a "flawed" infection.

Isnt it the same idea as EVERY game like this where one person is immune? That its because of some genetic quirk or something? I am Legend...and so on.

She's the One.

Human evolution, or maybe she has some crazy anti-fungal brain fluid.

think she is just a bit special like Jesus.

Well what was a bit disappointing was that she wasn't exactly immune to it. From what I gathered, the virus started growing in her and then stopped without affecting some part of the brain that causes the aggressive behavior seen in other infected. This kinda makes you wonder if she would remain "immune" or if it would suddenly start growing again later down the road.

Can she infect other people?

She isnt immune at all. The strain in her was a mutated version, and not harmful to humans.

I think it's implied that it's more of a genetic fluke more than anything. Perhaps her being born into the world after the fact had something to do with it. Maybe knowing more about her parents and what they were exposed to would give answers.

Yes. She makes a point of biting David to get him infected which kind of back fires when it makes him go all extra crazy while hunting her down.

That was never confirmed. She initially bit him just as a means of desperation, and then I would imagine she screamed that she was also infected through quick thinking to bide her those precious few seconds while David's confused.

I don't think you can pinpoint that as the thing that made him go crazy. Dude wasn't right to begin with.

Broadly speaking with genetics, there is always people either immune or highly resistant to just about anything - that being how evolution works. I figured that was the case with Ellie, but some of the later collectables did seem to say that the fungus had mutated in her. I don't exactly know how that works, considering that section she walked though all the spores, but really, I don't think it was important.

maybe her parents where hippies and did tons of mushrooms. the magic ones. before she was born? or perhaps she was dropped on her head as a baby, would explain all the weird noises she makes, you just think its her making music sounds, but perhaps she is just tarded. trying to whistle? at her age? maybe its a psyonic defence against spores and infections?

1 in 10 Europeans are immune to HIV, it's our genetic variability that keeps the species going

I want to say one of those recordings in the hospital talked about how the membrane around her brain stopped the fungus from getting to and infecting her brain.

I want to say that in one of the audio logs/collectables in the hospital says that when blood is removed from her the fungus starts to grow like it would normally.

I wanna preface this by saying that I don't think any of this matters in a narrative sense and debating if Ellie really needed to be killed to engineer a vaccine, whether or not she'll turn in the years to come, etc. undermines the well earned moral quagmires in a very pedantic fashion. That said, the letter from Ellie's mom you can find in her backpack states both that the letter was written only a day after Ellie's birth, and that Ellie's mom knows she'll be dead very soon. While I suppose she might be anticipating her death based upon a feud she and Marlene are involved in, the certainty with which she words it - "a life ( referring to hers) that's about to be cut a bit short"- makes me doubt that. And the exuberance with which she regards her baby daughter makes me think she'd like nothing more then to stick around, so suicide's off the table. Which leaves a sequence of events in which Ellie's mother was bitten while pregnant, then almost immediately after gave birth and made sure Marlene would care for Ellie. A day or so later she would have succumed to the virus. This could account for Ellie's immunity, or as the surgeon seemed to think, her resistance. I'm probably just missing some obvious alternative, but upon reading the letter, the above is what jumped to mind.

Aren't there always people immune to some kind of infection?

Ellie may very well have been one of many. But at the RATE at which people were being indiscriminately slaughtered (by hunters, by each other, by infected interested in more than just dolling out scratches [not to mention the MEANS by which you discover that you're immune]), most people who are/were immune probably don't know it/never had a chance to know it.

Bit more depressing when you think about it that way.

If you read the letter from her mom in the Winter chapter, she alludes to Ellie learning about her, or something like that, very soon. But it's not elaborated on. Maybe there's something to that? Some kind of experimentation? She definitely had a tie to Marlene, who was head of the Fireflies. There are lots of little threads like that which make me think there is a lot of areas to be explored if they were to expand the universe with books or more comics. (I dunno what is and isn't covered in the current comics, I only read teh first one)