Could've been a lot better.
The movie felt lazy to me. No explination to why she came back or why it stopped. Was it happening all over? Why wasn't there doctors, reporters, government officials/military all over the town? Later on it seems like there was more of an outbreak, but you never see any of it. It just seemed like a lot of odd choices and omitting of key plot.
And just my own personal preference, I hated all the improv. You can tell (at least I can) when they are improvising, cause there's a tone in the voice and a lot of times the dialogue feels unnatural.