system
Given the following post, respond as if you're commenting on Reddit:
human
[The last of us] Is Ellie going to grow up fine anyway?

So Joel chooses to save the kid, yay him. However, it seems to me that what Ellie has is more of a resistance than an immunity. That wound wasn't healing, and looked pretty manky. And the fireflies found some spread of infection in her brain, just not as aggressive as normal, or enough to impair her faculties.

Yes, Ellie may not have turned in the usual time frame, but what's to say she won't slowly become an infected in a few years?
gpt
The 'infection' in her brain is what's actually causing her complete immunity. It was caused by some kind of anomalous genetic interaction that occurred right after she was bitten. That's why the wound looks kinda gross - it's because the wound *did* fester for a bit before the mutation in her brain kicked in and gave her full immunity to the disease.

As far as we know, her immunity will last until she dies. Of course, if there was some other trigger to make her brain mutate in a different way, or if she was to lose that part of her brain in some kind of accident, then she would probably fully turn into one of the infected.