The Mirror Lied - story explanation

Explanation:
I think "birdie" is a codename for an infectious agent. Leah is probably a researcher that has developed a vaccine against "birdie" and has plans to profit from it after another personally spreads the disease. "A bird landed on water today" indicates that a water supply was contaminated. "It flew away" tells how quickly it spread. Leah was suppose to stop "birdie" by releasing the vaccine but then "Oh, it's too late". "birdie" was too fast and "flew" over Europe. There's no one left to save. Consumed with guilt Leah infects herself, succumbs to her fever, and slips into a coma to eventually die. Letting "birdie" take her away.

Though that doesn't explain how "birdie" lies to her or the meaning of the note with different times on it.