Rheumatoid arthritis flare up / FELT LIKE A RHEUMATOID ARTHRITIS FLARE UP/FELT ACHES, PAINS/Joint pain / PAIN IN ALL JOINTS/fatigue; Fall / FELL AND INJURING LEFT KNEE; Knee injury / FELL AND INJURING LEFT KNEE; Osteoarthritis; Feels bad / FELT HORRIBLE; This spontaneous case was reported by a consumer and describes the occurrence of RHEUMATOID ARTHRITIS (Rheumatoid arthritis flare up / FELT LIKE A RHEUMATOID ARTHRITIS FLARE UP/FELT ACHES, PAINS/Joint pain / PAIN IN ALL JOINTS/fatigue) in a 63-year-old female 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) solution for injection for Rheumatoid arthritis.    Concurrent medical conditions included Rheumatoid arthritis.   On 02-Feb-2021, the patient started ADALIMUMAB (HUMIRA) (Subcutaneous) Solution for injection in pre-filled pen. In 2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. In 2021, received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. In 2021, the patient experienced RHEUMATOID ARTHRITIS (Rheumatoid arthritis flare up / FELT LIKE A RHEUMATOID ARTHRITIS FLARE UP/FELT ACHES, PAINS/Joint pain / PAIN IN ALL JOINTS/fatigue) (seriousness criterion medically significant), FALL (Fall / FELL AND INJURING LEFT KNEE), JOINT INJURY (Knee injury / FELL AND INJURING LEFT KNEE), OSTEOARTHRITIS (Osteoarthritis) and FEELING ABNORMAL (Feels bad / FELT HORRIBLE). In 2021, RHEUMATOID ARTHRITIS (Rheumatoid arthritis flare up / FELT LIKE A RHEUMATOID ARTHRITIS FLARE UP/FELT ACHES, PAINS/Joint pain / PAIN IN ALL JOINTS/fatigue) and FEELING ABNORMAL (Feels bad / FELT HORRIBLE) had resolved. At the time of the report, FALL (Fall / FELL AND INJURING LEFT KNEE) outcome was unknown and JOINT INJURY (Knee injury / FELL AND INJURING LEFT KNEE) and OSTEOARTHRITIS (Osteoarthritis) had not resolved.            No concomitant medications were provided by the reporter.  The patient received HUMIRA(Solution for injection in pre-filled pen)(ADALIMUMAB).  It was unknown if patient was enrolled in a COVID-19 Vaccine Trial.  The reporter's causality for the event(s) of osteoarthritis and fell and injuring left knee onset in 2021 was not provided. The reporter's causality for the event(s) of felt horrible, felt aches, pains, felt like a rheumatoid arthritis flare up, pain in all joints and fatigue with Humira(adalimumab) was a reasonable possibility. The reporter's causality for the event(s) of fell and injuring left knee onset in 2021 with Humira(adalimumab) was no reasonable possibility.  No treatment medications were provided by the reporter.  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.  CC: This spontaneous case concerns a 63-year-old, female patient with a concurrent condition of rheumatoid arthritis treated with adalimumab, who experienced an unexpected, medically significant AESI Rheumatoid arthritis (RA) flare up in association with a dose of mRNA-1273 vaccine. Exact onset latency of the event RA flare up relative to vaccination cannot be determined with unknown event's onset date and vaccination dates. Reportedly, the patient felt horrible with pain in all joints and fatigue as well as osteoarthritis on an unknown date. She also fell and injured her left knee on an unknown date. Outcome of the event RA flare up was reported as resolved. Vaccination history included a 2-dose primary series of mRNA-1273 vaccine. Patient's underlying rheumatoid arthritis remains a confounder in this case. The benefit-risk relationship of mRNA-1273 is not affected by this report. Event's seriousness assessed based on medical judgement.   Reporter did not allow further contact; Sender's Comments: This spontaneous case concerns a 63-year-old, female patient with a concurrent condition of rheumatoid arthritis treated with adalimumab, who experienced an unexpected, medically significant AESI Rheumatoid arthritis (RA) flare up in association with a dose of mRNA-1273 vaccine. Exact onset latency of the event RA flare up relative to vaccination cannot be determined with unknown event's onset date and vaccination dates. Reportedly, the patient felt horrible with pain in all joints and fatigue as well as osteoarthritis on an unknown date. She also fell and injured her left knee on an unknown date. Outcome of the event RA flare up was reported as resolved. Vaccination history included a 2-dose primary series of mRNA-1273 vaccine. Patient's underlying rheumatoid arthritis remains a confounder in this case. The benefit-risk relationship of mRNA-1273 is not affected by this report. Event's seriousness assessed based on medical judgement.