Rat is still afraid

Hi! I adopted 3 girls back in April from a school I go to. Two of them love me and don’t mind being held but the third one still is unsure about being held. She’ll let me pet her but I cannot pick her up without her struggling and I don’t like stressing them out if I can. I am going to school for vet tech, they were used for restraint and injections. Does it have to do with that? Will she come around eventually? She was used the most but she isn’t aggressive at all

Not all rats like to be picked up and held ...... but it sounds like she likes you since she lets you pet her
As she ages she will likely become more willing to be handled,
Younger girls are often too busy and independent to enjoy being held.
And as you suggested, being restrained and used for injections would have been a very traumatic experience and would have effected her. As time passes you may find that when the rats are out playing in their rat safe area with you, she will start to come to you, climb up on your lap for a cuddle and then take off again to run and explore ...... she will likely gradually become closer to you, on her own terms.

Glad that you gave the 3 girls a good home.
Hard to believe that a school that trains vet techs would exploit and abuse animals like that

It’s not abuse.... My instructors take very good care of the rats and when they notice some are becoming aggressive, they make arrangements ASAP to have them adopted. The instructors are careful with them but sadly my classmates are not

Not all of them become aggressive. They arrange to try and have them adopted as soon as possible to avoid further stress. It’s kinda a research facility/school

We've adopted rats from vet schools and most remain quite skittish. We just let them be and let them come around on their own terms.

That makes me happy to hear. She has nothing to fear from me, i just hope one day she comes around