I'm staying away from any vaccines while I have PMR too. Given that the adjuvants in vaccines are there specifically to cause a stronger immune response to the vaccine, I'm not willing to push my immune system when it's already being messed up by PMR and the meds.

The adjuvant in Shingrix is Quillaja saponaria, from the soapbark tree which is related to digitalis and very high in oxalates, something I'm currently avoiding. It's mildly toxic which is what makes the immune response stronger. It will probably be okay for most people, but it's not for me at the moment.