One or Two Week Methotrexate Discontinuation on Efficacy of Influenza Vaccination in Rheumatoid Arthritis.

Inclusion Criteria: * Males or females ≥ 19 years of age at time of consent * Have a diagnosis of RA per ACR criteria * Must understand and voluntarily sign an informed consent form including writing consent for data protection * Stable doses of methotrexate over the preceding 6 weeks Exclusion Criteria: * Pregnant or lactating females * Previous anaphylactic response to vaccine components or to egg. * Acute infection with T \>38°C at the time of vaccination * History of Guillain-Barre syndrome or demyelinating syndromes * Blood transfusion within 6 months * 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