The manner in which Sarah becomes aware of the outbreak is slightly altered in the HBO adaptation, but the end result is the same: Sarah, Joel, and Tommy attempt to flee to safety in their car, but are met with an accident. After Tommy and Joel are briefly separated, Joel assists the injured Sarah through chaotic alleyways, and they are saved from the infected by an officer. This is when tragedy strikes: Despite not being infected, Joel and Sarah become targets for the military, who seem to be killing innocents to avoid the risk of an infected populace. Although Tommy intervenes, it is too late for Sarah.
During the press event, Luna explained that the scene subtly highlighted how Joel was unable to accept the reality of Sarah being shot, whereas Tommy had to be more vigilant and urge his brother to keep moving. This is a devastating sentiment to relay in such an emotionally-charged scene, and Luna talked about Tommy’s role in that dire, life-or-death situation:
“I know what that wound is and I know what happens … I’ve seen it before and I am [reacting] quickly in that scene. I kind of walk off and I have to be at the ready, I have to be standing guard. At any moment, they can descend on us … That was really a rough [scene to shoot] that night. I was both looking forward to and dreading that scene. That was a big one.”
Thanks to his background, Tommy knows what a fatal gunshot wound looks like and instantly realizes that his niece cannot be saved. Surrounded by infected runners and officers willing to shoot innocents, Tommy knows there is no time to grieve and is forced to assume a more vigilant/proactive role to ensure that Joel makes it out alive.