Seronegative rheumatoid arthritis; Revaccination with different COVID-19 vaccine; Interchange of vaccine products; This spontaneous case was reported by a physician and describes the occurrence of RHEUMATOID ARTHRITIS (Seronegative rheumatoid arthritis) in a 30-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 066F21A) for COVID-19. The occurrence of additional non-serious events is detailed below.     Previously administered products included for Product used for unknown indication: Pfizer (Dose Number: 1 Batch/Lot No: EK5730 Anatomical location: Left arm Route of Administration: Intramuscular) on 21-Dec-2020 and Pfizer (Dose Number: 2 Batch/Lot No: EL3246 Anatomical location: Left arm Route of Administration: Intramuscular) on 11-Jan-2021. Past adverse reactions to the above products included No adverse event with Pfizer and Pfizer. Concurrent medical conditions included Drug allergy (Unknown historical drug).    On 19-Nov-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 19-Nov-2021, the patient experienced COVID-19 IMMUNISATION (Revaccination with different COVID-19 vaccine) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products). On 25-Jan-2022, the patient experienced RHEUMATOID ARTHRITIS (Seronegative rheumatoid arthritis) (seriousness criteria disability and medically significant). The patient was treated with METHOTREXATE at an unspecified dose and frequency and PREDNISONE at an unspecified dose and frequency. On 19-Nov-2021, COVID-19 IMMUNISATION (Revaccination with different COVID-19 vaccine) and INTERCHANGE OF VACCINE PRODUCTS (Interchange of vaccine products) had resolved. At the time of the report, RHEUMATOID ARTHRITIS (Seronegative rheumatoid arthritis) had not resolved.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   No concomitant medication information was provided. Events Arthritis and Hand deformity subsumed under the event Rheumatoid arthritis   The patient was not diagnosed with COVID-19.  It was unknown the patient had been tested for COVID-19 since the vaccination  Device Date : 13-Oct-2022  Company Comment: This is a spontaneous case concerning a 30 year-old, male patient with no reported medical history, who experienced the serious (due to medically important condition and disability) unexpected, AESI of Rheumatoid arthritis, which occurred approximately 2 months after the mRNA-1273 vaccine, received as the third dose of COVID-19 vaccination schedule. Patient reported Inflammatory joints and hand deformities and was diagnosed as seronegative rheumatoid arthritis. He received treatment with Methotrexate and Prednisone. The outcome was reported as not recovered. Additionally, Interchange of vaccine products and Revaccination with different COVID-19 vaccine (vaccination with two doses of COVID-19 vaccine Tozinameran) was noted in the case. No further clinical information was available for medical review.  The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.; Sender's Comments: This is a spontaneous case concerning a 30 year-old, male patient with no reported medical history, who experienced the serious (due to medically important condition and disability) unexpected, AESI of Rheumatoid arthritis, which occurred approximately 2 months after the mRNA-1273 vaccine, received as the third dose of COVID-19 vaccination schedule. Patient reported Inflammatory joints and hand deformities and was diagnosed as seronegative rheumatoid arthritis. He received treatment with Methotrexate and Prednisone. The outcome was reported as not recovered. Additionally, Interchange of vaccine products and Revaccination with different COVID-19 vaccine (vaccination with two doses of COVID-19 vaccine Tozinameran) was noted in the case. No further clinical information was available for medical review. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.