The goal of this clinical trial is to learn if methotrexate discontinuation affect on immunogeneity of shingrix in RA patients. The main questions it aims to answer are: Discontinuation of methotrexate after shingrix immunization increase efficacy of the vaccine in patients with RA ? Researchers will compare humoral and cell-mediated immunity against herpes zoster in RA patients who are vaccinated by shingrix, and compare these immunity between RA patients with MTX discontinuation and MTX continuation groups. Participants will: Vaccinated with shingrix twice. MTX continuation group will keep taking MTX after shingrix vaccination, whereas MTX discontinuation group will stop MTX for 2 weeks after shingrix vaccination. Visit the clinic at baseline (first shingrix vaccination), 2 months later for 2nd shingrix vaccination, then 3 \& 6 months later from baseline to achieve blood sample.