I Have Been On Predosone For Years Now On 25-35

I have been on Predosone for years now on 25-35 mg daily (Myastemia gravis) was told to get shingles vaccine .I was told and read that I may have a promblem with the vaccine.my neurologist said to ask my liver Doctor took the cure with Harvoni been over a year and clean with liver. I'm not sure what to do? YYYY@YYYY . Thank you