In contrast to the game series, in the TV series of The Last of Us it is not spores that will spread the infection: such a solution would not have worked within a TV production, as explained by executive producer Craig Mazin.
Anyone who has recently played The Last of Us Part 1 is well aware that in some sequences characters are forced to wear gas masks precisely to avoid inhaling the spores carrying the infection, but that will not happen in the TV series.
Apparently, the problem lay precisely in having the actors wear masks constantly: an element that the show’s writers deemed unsuitable for that kind of context, and thus decided to make an albeit important change to the story.
One positive implication is that, even if this flap is waived, the television series will attempt to explain more clearly what happened to the world and exactly how the infection that turned so many people into ferocious mutants advanced, and forced the survivors to enclose themselves within fortified cities.
Speaking of which, Neil Druckmann has said that the TV series of The Last of Us will not make the same mistakes as Game of Thrones, meaning that it will stay true to the original material and will not make changes for the sole purpose of provoking a reaction in viewers.