The Last of Us season 1 leaves a lot of questions open about Ellie's immunity to the Cordyceps brain infection, with viewers wondering if her blood gets turned into a cure in the original game. Although the doctors in The Last of Us universe initially seem to believe that Ellie can be used to make a cure, this storyline is never resolved. However, with a whole other story being told in The Last of Us Part II that hasn't yet been seen in the HBO show, there's a possibility that Ellie's immunity could create a cure in the sequel.
The Last of Us season 1 ending is out, wrapping up the events of the original game. In episode 9 of the HBO show, Joel and Ellie finally arrive at the Firefly hospital prepared for the doctors to turn Ellie's immunity into a cure. However, Joel soon finds out that in order to synthesize a cure, Ellie will have to die. This causes Joel to go on a massacre, killing nearly everyone in the hospital and getting Ellie out before she is harmed. During all of this, Ellie is on anesthetics, with Joel lying to her by explaining that the doctors couldn't make a cure from her immunity.
Ellie's Immunity Isn't A Cure In The Last Of Us (Nor Is Anything Else)
Joel kills the doctors before they try to synthesize a cure from Ellie's blood, meaning that nobody knows if a cure was actually possible in the HBO show. However, Ellie's immunity to the Infected is never used to make a cure in any of The Last of Us games, with this possibility never being resolved. The Last of Us Part II doesn't further explore a cure from Ellie, as she chooses to still believe that Joel was telling the truth. Even after Joel admits to lying, Ellie doesn't return to the hospital, with her immunity not being turned into a cure.
Sadly, Ellie's immunity isn't the only thing that isn't a cure. Throughout The Last of Us and The Last of Us Part II, a cure for the Cordyceps brain infection is never found, with no new possibilities popping up in the sequel. While surviving humans have gotten better at dealing with The Last of Us' Infected zombies, it seems that the monsters will be around forever, as the only doctor who could possibly make a cure was killed by Joel.
Why The Last Of Us Will Probably Never Reveal A Cordyceps Cure
Joel's rampage in The Last of Us season 1 finale pretty much cements that a cure for the Cordyceps brain infection will never be found. Education in the franchise's post-apocalyptic wasteland isn't great, meaning it would be very difficult to find a scientist with the skills to synthesize a cure. The only real hope would be scientists and doctors that have been around since before the outbreak, but by the day there are fewer of them. The Last of Us' Firefly doctor from the season 1 finale was one of the few hopes for humanity, but sadly, he was killed by Joel.
Another reason that a Cordyceps cure will never be revealed is that it would ruin the story of The Last of Us. Without Infected around to maintain the post-apocalyptic wasteland, The Last of Us wouldn't be much different than the normal world. Revealing a cure would fundamentally change the story, taking away what makes HBO's The Last of Us unique.
