SCP-5399 is an anti-memetic Musca Domestica
As far as I've seen on the site, 'antimemetic' generally isn't hyphenated. Also, shouldn't 'domestica' be uncapitalised?
-Ellingbrook.
Is the period at the end of this intentional? The rest of the signatures don't have one.
An unidentified member of Research and unidentified Security personnel stand next to the open containment chamber
This is extremely difficult to parse, to the point where I'm not even sure if it makes sense. I understand the meaning fully, but it probably needs rewording.
several drives in the security array were intact which provided relevant information about the destruction of Site-35.
Comma before which.
Security: Almost 45 minutes
There's no punctuation at the end of this dialogue.
Two bodies lie motionless at the far left-most edge of the camera feed.
Having both 'far' and '-most' feels redundant.
A member of site personnel is visible center-screen although their identity is obscured by a welder's mask
The log mentions that this person is a researcher, though the prior description goes no further than just a general member of personnel. I also feel that something like 'however' fits this sentence a little better than although, but that's entirely personal opinion.
The unidentified researcher adjusts their harness then kicks the exit of the room open.
Kicking open an "exit" seems like slightly weird phrasing.
On-site fire suppression systems are responding to the blaze but there appears to be substantial damage already.
Since both parts of this sentence are able to stand independently, there should be a comma before but.
Nearly thirty seconds pass before an insectoid buzzing is heard. The researcher's shoulders visibly slump. They begin sobbing and place their head in their hands.
I really like this as an ending. It shows the researcher's emotions without being at all forced or preachy.
This is sweet. The vagueness definitely works to your advantage here. I'm a fan of the proposed containment updates and the back and forth between the researchers about its true nature and the lack of a single, definitively correct answer by the end is an interesting choice which totally pays off. Each breach progresses the narrative well, and none of it dragged even for a second.
A solid, enthusiastic upvote from me, for the perfect mix of humour and seriousness taken in a unique direction.