The fact that Ellie is immune is closely tied to “The Last of Us.”
This HBO adaptation of the popular video game has been a hit with both viewers and critics since its premiere in January.
The show and the game take place in a future where civilization has been ravaged by an epidemic of Cordyceps, a parasitic fungal disease.
For 20 years, the virus has spread while the infected roam the Earth in search of new hosts.
A resilient survivor named Joel (Pedro Pascal) is tasked with escorting a teenage girl named Ellie (Bella Ramsey) across the United States to a lab, where her blood can be used to create a vaccine.
Infected, FEDRA members, Hunters, cannibals, and a few allies all inhabit the world that Joel and Ellie explore together throughout most of the game.
The mystery of Ellie’s immunity to the disease remains a central theme.
After being bitten by an infected woman while exploring an abandoned mall with her friend and potential romantic interest, Riley (Storm Reid), she quickly learns that she is immune.
The two then decide to engage in mortal combat. Fortunately, as the days pass, Ellie never succumbs to becoming one of the mindless infected.
In the show, most people are so astonished by Ellie’s immunity that they don’t even question it.
However, the origin of her immunity is vital. It might be possible to replicate this genetic miracle if it’s not just a coincidence.
The Reason Behind Ellie’s Fungal Immunity
Anna, Ellie’s mother (played by Ashley Johnson), appears at the start of episode nine.
She is experiencing labor contractions while attempting to outrun an unseen foe.
She attempts to enter what she believes to be a safe house by shouting, “It’s me,” but no one is there to hear her.
Her water breaks as she ascends the stairs to the main floor of the house. She sits on the floor and closes the door behind her to rest. An Infected zombie is pursuing her, and her only defense is a knife.
After being bitten, she manages to kill the zombie with the knife.
Anna gives birth while they are battling, and she hears Ellie’s cry just as she feels the bite on her leg.
With pride and affection for her “tough” newborn daughter, the mother cuts the umbilical cord and then cradles her.
The leader of the Fireflies, Marlene (Merle Dandridge), unexpectedly arrives that night and discovers Anna and the infant.
Anna explains that she was bitten right after giving birth, but her baby, Ellie, is safe because she didn’t breastfeed.
Furthermore, Anna urges Marlene to take Ellie to Boston but warns that if she does, she will have to kill her best friend to prevent Ellie from becoming infected.
After much contemplation, Marlene gives in.
Unraveling Ellie’s Immunity
After the Fireflies have captured Joel and Ellie in the present day, Marlene explains to Joel the reason behind Ellie’s immunity.
She reveals that “our doctor believes that the cordyceps in Ellie have grown in her since birth,” indicating that she must have known that her friend had deceived her about the timing of her infection.
This is what grants her immunity; the typical cordyceps mistake her for being cordyceps.
Joel plans to extract the immunity from her, cultivate the cells in a lab until they can produce the necessary chemical signals, and then distribute them to the public.
They believe it has healing potential.
However, since cordyceps spreads through the brain, they would have to kill Ellie to eradicate it.
The Fireflies did not inform Ellie about the procedure, and Joel is not going to let them execute her.
What Was the Cause of Ellie’s Immunity?
This theory has yet to be fully substantiated over the years, as numerous fans have noted in Reddit threads.
The opening scene in The Last of Us Season 1 finale reveals why Ellie is immune to the cordyceps infection, though it’s currently only canon for the HBO series. https://t.co/5dwIWMqixa pic.twitter.com/YFbX6hGwlD
— IGN (@IGN) March 14, 2023
First, why wouldn’t Ellie have triggered FEDRA’s virus scanners over the years if she had the infection from birth?
If she had tested positive for the virus, she would have been barred from attending a FEDRA institution.
After being bitten, she is convinced she will become a zombie; she shows no signs of realizing she may be immune.
Some have speculated that Ellie’s immunity to the fungus was primed by her prenatal exposure to even trace amounts of the organism, similar to how a vaccine primes the immune system.
Ellie’s immune system lights up on fungal scanners in the game, but the surgeon’s testing reveals that she isn’t fighting off an infection.
Her white blood cell count was expected to be harmful to the fungus.
Some have speculated that this is all a coincidence and that the strain of fungus that Ellie contracted had a mutation that prevented it from transforming anyone else who came into contact with it.
However, that’s not true either, as Riley (Storm Reid) and Ellie were both bitten by the same zombie and turned.
But that’s the crux: the ambiguity. Marlene doubts that Ellie has the cure, but she is willing to kill her nonetheless.
Furthermore, Marlene’s desperation to eradicate the virus is only underscored.
Is Ellie’s Immunity a Cure?
Ellie’s immunity may not have been scientifically significant enough to develop a vaccine or treatment.
There are no specific vaccinations for the fungus available for use in clinical practice.
In February, NBC News reported that the development of such products had commenced but would likely only hit the shelves for a short time.
And this is in a more advanced and technological world than the dystopian future of “The Last of Us.”
Vaccinologist Christine Rollier predicted in a 2016 video for the Wellcome Trust discussing the game that finding a treatment for the infection, should it exist, would take 20 years.
Rollier also stated that there’s “no chance” Ellie’s tissue was used to create a vaccine in another video for the project. “That’s not how a vaccine or the immune system works,” she said.
She clarified that Ellie’s immunity did not prevent the disease but rather that she is “not susceptible” to the fungus.
She drew an analogy between this and the fact that some people are immune to HIV because they carry a mutation in a protein that the virus cannot adhere to.
However, she did mention that Ellie’s anti-fungal antibodies were used to develop new ones, but the Fireflies have no interest in that whatsoever.
In The Last of Us, can Ellie infect others?
Who or what is infected? They were once humans, but the brain-infecting fungus Cordyceps has slowly transformed them into monsters.
However, it would be unfair to call them zombies.
“The infected” are not reanimated corpses but rather living hosts that this parasite has taken over.
Its sole purpose is to spread, and in The Last of Us, it does so via bites or airborne spores.
Due to the rapid progression of the infection to the brain, the host cannot be treated without causing their death.
Co-president Neil Druckmann and his team went to “great lengths to create a complete biological cycle for these entities.”
The entire life cycle of the fungus, from infection to death, is explained here.
The question of why Ellie is immune has kept fans captivated by the game and the show.