Introduction:
Rheumatoid arthritis (RA) is a chronic autoimmune disease that, if uncontrolled, leads to progressive joint damage. The potential immunomodulatory effects of COVID-19 vaccination on autoimmune disease activity remain an area of investigation.

Case report:
We describe a 79-year-old woman with a 40-year history of RA, initially treated with methotrexate and, since 2008, with leflunomide (20 mg/day) in combination with corticosteroids (Urbason 8 mg/day) and non-steroidal anti-inflammatory drugs (NSAIDs). During the COVID-19 pandemic, after receiving three doses of the Pfizer vaccine, she discontinued leflunomide due to concerns about infection risk. Upon evaluation in 2021, despite residual joint damage in the hands, clinical and radiographic assessments confirmed inactive RA. Over a three-year follow-up, radiographs demonstrated stable erosions and osteopenic changes, corticosteroid therapy was progressively reduced, and anti-citrullinated protein antibody (ACPA) titers declined by approximately 50% compared to pre-vaccination levels.

Discussion and Conclusions:
This case suggests a potential immunologic “reset” following COVID-19 vaccination, contributing to sustained RA remission despite discontinuation of a conventional disease-modifying antirheumatic drug (DMARD). Although the precise mechanisms remain unclear, this observation aligns with emerging evidence that vaccine-induced immunomodulation may influence autoimmune disease activity. Further research, including larger controlled studies, is warranted to explore the potential benefits of COVID-19 vaccination in RA management.