Why Is Ellie Immune In The Last Of Us? Season 1 Finale Provides A Hint But Still No Answers

gamespot.com:

In Naughty Dog's The Last of Us video game, main character Ellie is immune to the cordyceps fungal infection that caused a pandemic that propelled the world into chaos and despair. Ellie is immune to the infection, but why, and how? The game never provides an answer, but the Season 1 finale of HBO's series provides clues, it seems, to the origin of Ellie's immunity. Spoilers for The Last of Us follow below.

In the Season 1 finale, we get a flashback that shows Anna (Ashley Johnson), pregnant with Ellie, trying to outrun an infected person, only to be cornered in an abandoned house and attacked. She kills the infected, and during the struggle, gives birth to Ellie. Anna is bitten during the encounter.

Anna cuts the umbilical cord, but the show leads us to believe the cordyceps infection was indeed spread to Ellie. Marlene (Merle Dandridge) soon arrives on the scene. Anna pleads with her to kill her and take Ellie, assuring Marlene that she gave birth before she was bitten--this is a lie.

Marlene takes Ellie and initially says she can't bring herself to kill her longtime friend. But she eventually re-enters the room and quickly shoots and kills Anna. She then takes Ellie to Boston with her.

But how is Ellie immune? The show doesn't tell us, and while the game contained some clues as well, neither material provided a definitive explanation.

Neil Druckmann, who wrote the original game and some of the TV series, told Entertainment Weekly that the flashback scene with Anna provides a hint that should give people «theories as to why Ellie is immune.» However, neither the game nor the TV series explain it outright or conclusively.

For more on The Last of Us Season 1 finale, check out GameSpot's interview with Marlene actress