Explained: Why is Ellie immune in The Last of Us?

A still from The Last of Us (Image via HBO)
A still from The Last of Us (Image via HBO)

The Last of Us, one of the most awaited shows of 2023, finally came out with its debut episode on Sunday, January 15, 2023. Based on the popular PlayStation game of the same name, this HBO show follows the post-apocalyptic quest of a smuggler, Joel (Pedro Pascal), as he attempts to escort a young girl, Ellie (Bella Ramsay), across the United States in the wake of a deadly fungus that "turns" humans.

The first episode revealed a lot of information, including some highly intriguing ones for those who haven't played the game. This included an explanation as to why Ellie was valuable. The first episode's ending revealed that Ellie was immune to the fungus that had nearly claimed humanity. She even showed a bite on her hand.

Though this might be completely clear to The Last of Us players, others may not get this very well.


The Last of Us: Why did the fungus not affect Ellie?

Ellie's immunity to the virus was both the driving factor and the central plot of The Last of Us. In a time where humanity is on the brink of extension due to a fungus pandemic, only one human can resist it. Ellie seems to have no effect from the bites of other infected humans.

At the end of the episode, Ellie shows a bite on her arm that she received weeks ago. This was in contrast to how things worked in that universe. Infected people usually turned completely within 48 hours, making Ellie's case very different. This scene indicated that Ellie did get the fungus in her system but was not affected by it like others.

While both The Last of Us games and the HBO series refused to explain the biological process through which Ellie resists the fungus, it has been attributed to genetic factors. Ellie could resist the fungus because of a probable mutation in her genes, something that helped her either fight the fungus or exist with it symbiotically.

It was something Ellie had from birth and not something she received later. This could have been completely random as well. But this forms the narrative base of The Last of Us and explains why Ellie is so valuable. Her genetic material or a study of her system could be the key to fighting off this disease.

However, there is one theory that is popularly accepted about Ellie's immunity. The theory is that Ellie's mother, a nurse by profession, was infected with the fungus when she was pregnant with Ellie, leading to the infant getting exposed to the Cordyceps infection. This could have given her the ultimate immunity to the disease.

This theory was never confirmed in the game but can be used in the HBO show, which will likely explore Ellie's past at some point.


The second episode of The Last of Us will premiere on January 22, 2023.

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Edited by Shreya Das