[TOMT] Searching for a specific zombie movie

Hi, I need help finding a specific zombie movie I seen as a kid. It was released no later than 2012 but no earlier than 2000. Here’s what I remember:

First (early) sign of infection: nosebleed

Scenes I vividly remember:

• A group of survivors (SV) pulling up to a US military base where all the military members (MM) were infected but still had their guns and were acting somewhat “normal”. From afar, the MMs looked as if they weren’t infected, and I’m pretty sure they still talked. This scene takes place during mid-day.

-Smaller group of SVs walking down a hospital/laboratory’s hallway in a line . An infected scientist (IFS, this zombie was important because he worked on/created the virus) crawling in the ceiling vent above SVs drops down, quickly grabs the last person (LP) of the line without making a sound, and goes back into the vent. Next thing you know, the LP’s body drops in front of the group from the ceiling. (This scene gave me a fear of tight halls with ceiling vents so I remember it like the back of my hand, lol)

-There was a scene that showed video logs of the IFS turning into a zombie.

-There was another scene where the SVs assumed one of them were infected because they had a nosebleed but they weren’t, and it leds to a fight between the falsely accused and and the accusers. I believe the falsely accused was covering for someone else who was infected (a loved one possibly—idk I could be mistaken). I also remember one of the women in this scene had a bright fire red low v-lined shirt (I remember thinking it looked pretty on her)

(Please don’t say that movie with Nick Cannon. I just watched it, it’s not it 😭)