Wait... so they are free of any microbes? Like...at all? Do they even have immune system at all? What about other lifeforms on their world? What if an insect bites one? Or if they are met with fungi of any kind?

They are obviously not free of ANY microbes, but they do their best. They do have an immune system, but they're so reliant off their ability to quickly make vaccines, it's better off to say they don't have one at this point. There's always a chance bacteria gets into them and doesn't hurt them, but the stakes of it actually causing damage are much higher.
They live on a heavily regulated and maintained space station in the middle of an asteroid field in andromeda. Mainly regulated by another species I have called the "Nebula Xeviors" which are more advanced than the Spectarrians. So in the case of a bad scenario, the Xeviors are on the case.
Due the station being heavily regulated, there are no insects.
Met with a fungi of any kind? That's met with isolation and inspection. It wouldn't be the first time they've done it. As you can imagine, the system isn't perfect, but it's extremely impressive for what it can pull off in terms of keeping their entire race safe. They're essentially all lab rats in a big space tube. Except they do the research. They form their own society. They have their own culture, and the space station is by no means small-- Spanning around SEVERAL asteroids. Needless to say, it has it's own homey feeling. Even it's own plant ecosystem! (Considering it is an ecosystem, it can introduce threats, so the plant life is also heavily monitored and maintained by their safety groups.)

I...got to be totally honest. That's a pretty solid piece of worldbuilding.
Damn. Awesome to hear all that and to learn! Color me impressed :D

Sounds like a lor of effort, but apparently it really pays off if they can really maintain such high lvl of hygiene.