It only has a half-life of a few days. I don't think it can be sexually transmitted. There is zero evidence that it can be, and no biological path that I can see, but biology can be tricky, so who knows. Regardless, after 2 weeks or so it most definitely can't be, because it will all be gone from her system.

Since the spike protein that the vaccine produces is the worst part (mostly), the same things that work for the virus also are good for the vaccine. Make sure she gets plenty of Vitamin D and Zinc with Quercetin prior to getting her next shot. Keep her on those things for two weeks. Also add plenty of Vitamin C.

Ivermectin is really good too, and I would recommend that. If getting Ivermectin is a problem you can get the horse dewormer stuff (the active ingredient is identical, the inactive ingredients are totally normal human food. Its just called horse dewormer, the name is irrelevant biologically, though not psychologically). If you are interested in that route and she would be willing I can give you the dosage and schedule.