They have to grant reasonable accommodations. Wouldn’t it be a reasonable to let you just keep doing whatever you’ve been doing since March 2020? Working remotely, wearing a stupid mask, keeping your distance, etc. If whatever you’ve been doing is so dangerous that you can no longer do it when a shot mandate deadline kicks in, your employer should have put you on leave a year and a half ago until it was safe to bring you back. If they had done that, they’d have a solid argument that you can only come back if you get the shot. Otherwise, it seems to be a slam dunk reasonable accommodation to simply be allowed to take the safety precautions your employer had in place before the shot became available.