Not sure when this movie was made but I watched it over 5 years ago.
The plot with a military like base in a zombie apocalypse, there multiple stages of infection ranging from just being sick to being a very dangerous killer zombie.
They have these blood test kits where it immediately tells you if you're infected or not, and they send out teams of soldiers with a doctor.
During the movie they find a child who is immune to the virus and the military team and doctor fight their way back to base. At the end of the movie only the doctor and kid are alive as they approach a gate into the base the doctor gives her hazmat suit to the kid so the guards wont shoot and the kid is brought into the base but the doctor gets shot by the soldiers.
I am fairly certain its not any of these movies:
Dawn of the Dead
Train to Busan
World War Z
I Am Legend