Rheumatoid arthritis flare up; Fatigue; Sore arm; This spontaneous case was reported by a consumer and describes the occurrence of RHEUMATOID ARTHRITIS (Rheumatoid arthritis flare up) in an adult male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.    Co-suspect product included non-company product ADALIMUMAB (HUMIRA) for Rheumatoid arthritis.    Concurrent medical conditions included Rheumatoid arthritis (Moderate to severe).   On 28-Jul-2020, the patient started ADALIMUMAB (HUMIRA) (Subcutaneous) at an unspecified dose. On 10-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 10-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 03-Nov-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On an unknown date, the patient experienced RHEUMATOID ARTHRITIS (Rheumatoid arthritis flare up) (seriousness criterion medically significant), FATIGUE (Fatigue) and PAIN IN EXTREMITY (Sore arm). At the time of the report, RHEUMATOID ARTHRITIS (Rheumatoid arthritis flare up) had not resolved and FATIGUE (Fatigue) and PAIN IN EXTREMITY (Sore arm) outcome was unknown.            No relevant concomitant medications were reported. Patient had Rheumatoid arthritis flare up of occasional pain in feet, hands, elbows, knees and back. It was unknown if patient was enrolled in a COVID-19 Vaccine Trial.  The reporter's causality of Humira for the event(s) of fatigue and sore arm with Humira(adalimumab) was no reasonable possibility. The reporter's causality of Humira for the event(s) of rheumatoid arthritis flare up of occasional pain in feet, hands, elbows, knees and back with Humira(adalimumab) was a reasonable possibility.  This case was identified as part of a retrospective clean-up activity where certain emails received in the Moderna mailbox were missed to be booked-in.  Company comment: This spontaneous case concerns an adult male patient with medical history of Rheumatoid Arthritis that was treated with ADALIMUMAB (HUMIRA), who experienced the unexpected, serious (medically significant) AESI of Rheumatoid arthritis (Rheumatoid arthritis flare up) among other non-serious events. The event occurred on an unknown date in context to third dose of mRNA-1273 vaccine. The Clinical course, Concomitant medication and treatment details were not provided, and the event outcome was not resolved. The medical history of Rheumatoid Arthritis remains a confounder to the event's Rheumatoid arthritis flare up. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report. Events seriousness was assessed as per medical judgement and available information.; Sender's Comments: This spontaneous case concerns an adult male patient with medical history of Rheumatoid Arthritis that was treated with ADALIMUMAB (HUMIRA), who experienced the unexpected, serious (medically significant) AESI of Rheumatoid arthritis (Rheumatoid arthritis flare up) among other non-serious events. The event occurred on an unknown date in context to third dose of mRNA-1273 vaccine. The Clinical course, Concomitant medication and treatment details were not provided, and the event outcome was not resolved. The medical history of Rheumatoid Arthritis remains a confounder to the event's Rheumatoid arthritis flare up. The benefit-risk relationship of the mRNA-1273 vaccine is not affected by this report. Events seriousness was assessed as per medical judgement and available information.