This spontaneous case was reported by a consumer and describes the occurrence of RHEUMATOID ARTHRITIS (RHEUMATOID ARTHRITIS FLARE UP) in an adult 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) for Rheumatoid arthritis. There was no reported medical history. Concurrent medical conditions included Rheumatoid arthritis. On an unknown date, the patient received dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form and ADALIMUMAB (HUMIRA) (Subcutaneous) Citrate Free. On an unknown date, the patient experienced RHEUMATOID ARTHRITIS (RHEUMATOID ARTHRITIS FLARE UP) (seriousness criterion medically significant), PAIN (BODY ACHES), SITTING DISABILITY (NOT ABLE TO SIT/ STAND/ LAY FOR LONG PERIODS OF TIME), DYSSTASIA (NOT ABLE TO SIT/ STAND/ LAY FOR LONG PERIODS OF TIME), MOBILITY DECREASED (NOT ABLE TO SIT/ STAND/ LAY FOR LONG PERIODS OF TIME) and PAIN IN EXTREMITY (ARM HURT). At the time of the report, RHEUMATOID ARTHRITIS (RHEUMATOID ARTHRITIS FLARE UP) had not resolved, PAIN (BODY ACHES) and PAIN IN EXTREMITY (ARM HURT) had resolved and SITTING DISABILITY (NOT ABLE TO SIT/ STAND/ LAY FOR LONG PERIODS OF TIME), DYSSTASIA (NOT ABLE TO SIT/ STAND/ LAY FOR LONG PERIODS OF TIME) and MOBILITY DECREASED (NOT ABLE TO SIT/ STAND/ LAY FOR LONG PERIODS OF TIME) outcome was unknown. The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown. 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. Concomitant medications were not reported. It was unknown if patient was enrolled in a COVID 19 Vaccine Trial. Treatment medications were not reported. The reporter's causality for the event(s) of rheumatoid arthritis flare up, body aches and arm hurt with Humira (adalimumab) was no reasonable possibility. the reporter's causality for the event(s) of not able to sit/ stand/ lay for long periods of time unknown onset, not able to sit/ stand/ lay for long periods of time unknown onset and not able to sit/ stand/ lay for long periods of time unknown onset was not provided. Company Comment: This is a spontaneous case, reported by a consumer, concerning an adult female patient with relevant medical condition of moderate to severe Rheumatoid arthritis, who experienced the unexpected serious (medically significant) adverse event of special interest Rheumatoid arthritis, reported as rheumatoid arthritis flare up, in the context of a dose of mRNA-1273 vaccine. Latency cannot be properly assessed since the event onset date was not provided. The patient also experienced body aches, inability to do prolonged sitting and standing, and arm pain. No further details about the clinical course, diagnostic procedures and treatments were provided. It was reported that the event Rheumatoid arthritis was not resolved. The medical condition of moderate to severe Rheumatoid arthritis remains as a confounder for rheumatoid arthritis flare up. The benefit-risk relationship of mRNA-1273 is not affected by this report. Sender's Comments: This is a spontaneous case, reported by a consumer, concerning an adult female patient with relevant medical condition of moderate to severe Rheumatoid arthritis, who experienced the unexpected serious (medically significant) adverse event of special interest Rheumatoid arthritis, reported as rheumatoid arthritis flare up, in the context of a dose of mRNA-1273 vaccine. Latency cannot be properly assessed since the event onset date was not provided. The patient also experienced body aches, inability to do prolonged sitting and standing, and arm pain. No further details about the clinical course, diagnostic procedures and treatments were provided. It was reported that the event Rheumatoid arthritis was not resolved. The medical condition of moderate to severe Rheumatoid arthritis remains as a confounder for rheumatoid arthritis flare up. The benefit-risk relationship of mRNA-1273 is not affected by this report.