To investigate the effect of MTX discontinuation for 1 week on vaccination response to Covid-19 booster vaccination in RA patients.

Inclusion Criteria:

• Males or females ≥ 19 years of age at time of consent
• Have a diagnosis of RA per ACR criteria
• Require methotrexate for RA treatment
• Subject to a Covid-19 booster vaccination
• Must understand and voluntarily sign an informed consent form including writing consent for data protection

Exclusion Criteria:

• Pregnant or lactating females
• Previous anaphylactic response to the vaccine components
• Any other rheumatic disease such as systemic lupus erythematosus, mixed connective tissue disease, dermatomyositis/polymyositis, and vasculitis except for secondary Sjogren's disease
• Any condition including laboratory abnormality which places the subject at unacceptable risk
• Subjects who decline to participate