I think The Last of Us finale just explained why Ellie’s immune

Bella Ramsey as Ellie in The Last of Us season finale trailer
(Image credit: HBO via YouTube)

In a bit of a surprise we didn't see coming, HBO's The Last of Us finale just added valuable information to the game's lore. At least, that is, for those who are willing to see this show as even slightly canonical.

We won't spoil how it all happened here, at the start of the article. No, we have a spoiler warning below that you'll need to cross first. But, first, let's give a moment to those who won't be so willing to accept this as the character's true story.

Yes, HBO's The Last of Us is far from a purely canonical story. In it, the cordyceps pandemic doesn't spread via spores, a pretty significant change that felt acceptable for the sake of the medium of TV. Nobody needs to see these characters talking through gas masks all day. On top of that, some characters (primarily Bill and Frank) have different stories.

But for those who think of The Last of Us show as just as valid as the game, let's break down what just happened.

An image indicating spoilers are ahead.

The Last of Us' original Ellie birthed HBO's Ellie

When we first meet Ellie's mom — who wasn't in the games — she's played by Ashley Johnson, which is a perfect coincidence. Johnson voiced Ellie in The Last of Us games, which makes her a perfect mother for Ellie. And we first meet the very-pregnant Anna (Johnson) as she's on the run from infecteds in the woods. 

She finally makes it to an abandoned house where she expected to find folks, but nobody's there. And making matters worse, her water breaks right before she can barricade herself into a room.

Ashley Johnson as Ellie's mother Anna in The Last of Us episode 9

(Image credit: Liane Hentscher/HBO)

And once an infected bursts in, clawing at her, Anna stabs it to death. But once newborn Ellie's cries wail out, Anna realizes she's been bitten by the infected. She then uses her pocket knife to cut the umbilical cord, and calls the child Ellie for the first time. 

There, you have it, the first ever reason to explain Ellie's immunity. Showrunners Neil Druckmann and Craig Mazin have added to Ellie's lore by giving her the smallest amount of an infection (similar to how vaccines work), and then her body developed a resistance.

Outlook: Marlene's doctors agree

Later, at the hospital, Marlene (Merle Dandridge) basically confirms my suspicions, or explains that the Fireflies' doctors agree with my assessment. 

While Ellie is being prepped for surgery, she tells Joel that their doctor believes that the cordyceps has been growing with her since birth, and it created an immunity. Of course, that's just a theory on their end. They never got to prove it. 

And one wonders if The Last of Us — as a show or game — will ever get a chance to confirm it. While The Last of Us season 2 will likely mirror The Last of Us Part 2, there is still no word about The Last of Us getting a third act. Though The Last of Us season 3 is already a topic on showrunners Craig Mazin and Neil Druckmann's minds.

Henry T. Casey
Managing Editor (Entertainment, Streaming)

Henry is a managing editor at Tom’s Guide covering streaming media, laptops and all things Apple, reviewing devices and services for the past seven years. Prior to joining Tom's Guide, he reviewed software and hardware for TechRadar Pro, and interviewed artists for Patek Philippe International Magazine. He's also covered the wild world of professional wrestling for Cageside Seats, interviewing athletes and other industry veterans.