In the game, yes, but in the world of The Last of Us, I'd doubt it--especially if Ellie has living relatives. She isn't going to be infected/immune in the sequel, as we've seen her kiss someone in the trailer, which would spread the infection.
Thereof, can Ellie swim in The Last of Us 2?
As director Neil Druckmann stated early on, hate and rage are two of the main themes of Ellie's journey through this game. Infamously, Ellie was unable to swim in The Last Of Us. In The Last Of 2, however, Ellie gains the ability to jump, which is an action Joel was unable to do in the first game.
Additionally, will Tommy be in The Last of Us 2?
Tommy hasn't been confirmed for the sequel, but his appearance would likely mean more information on the Firefly camp. That said, he'd probably have a small part in the game considering Joel isn't the focus.
Does Ellie hate Joel?
Ellie absolutely doesn't outright hate Joel, but the ending of TLOU was also a complete betrayal of her trust. If nothing else, Ellie is a teenager and Joel is her adopted father, essentially. Of course there's going to be friction, and that's not taking into account all the murder, kidnapping, etc.
Is Ellie's mom dead?
It's Ellie's mom, Anna. Although she was physically absent from The Last of Us, Ellie's mom's presence looms large. Anna died just after giving birth to Ellie, but left a letter behind for her daughter to remember her by. The name of the woman believed to be Ellie's mom is blacked out by exactly four dark squares.