I just got my first dose of covid vaccine. can i get a steroid injecting on my shoulder or will it effect the vaccine? i have osteoarthritis on my shoulders?

I would not get any steroid shot for 2 weeks to allow the vaccine time to trigger your immune system response without any interference. A focal steroid injection into the joint may not interfere as much as taking steroids by mouth. However, given the seriousness of the covid disease in many I would avoid anything that might reduce the vaccines effectiveness.

It depends on timing of the steroid injection and covid shot. It should not effect the vaccine

Since a steroid injection to the shoulder is elective, I see no reason why this could not be delayed at least 2-3 weeks after the second vaccination, and then it is very unlikely to have any immune compromise effect whatsoever.