Rheumatoid arthritis flair for 6 months; Arm where the shot was given ache; Dizzy; Fever in the right arm where the shot was given; Very bad headache/Headache; Sever fever; Red area around the shot; This spontaneous case was reported by a consumer and describes the occurrence of RHEUMATOID ARTHRITIS (Rheumatoid arthritis flair for 6 months) in a female patient of an unknown age who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.   On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient experienced RHEUMATOID ARTHRITIS (Rheumatoid arthritis flair for 6 months) (seriousness criterion medically significant), PAIN IN EXTREMITY (Arm where the shot was given ache), DIZZINESS (Dizzy), INJECTION SITE WARMTH (Fever in the right arm where the shot was given), HEADACHE (Very bad headache/Headache), PYREXIA (Sever fever) and VACCINATION SITE ERYTHEMA (Red area around the shot). At the time of the report, RHEUMATOID ARTHRITIS (Rheumatoid arthritis flair for 6 months) had not resolved, PAIN IN EXTREMITY (Arm where the shot was given ache), DIZZINESS (Dizzy), INJECTION SITE WARMTH (Fever in the right arm where the shot was given) and VACCINATION SITE ERYTHEMA (Red area around the shot) outcome was unknown and HEADACHE (Very bad headache/Headache) and PYREXIA (Sever fever) had resolved.            No concomitant medication was provided.  The patient stated that on the night of her second shot, she had a severe fever and a very bad headache. She ended up taking a migraine medication as the headache was so bad. That cut the fever and did away with the headache, but she still had a fever in the right arm where the shot was given. She had no problems after that, except the RA problems, however, from time to time, the arm where she had the shot given would ache.  Treatment included an unspecified medication for migraine for the event headache and that cut the fever also.  Company Comment: Based on the current available information and temporal association between the use of the product and the start date of the events, except Rheumatoid arthritis, a causal relationship cannot be excluded. Concerning the event Rheumatoid arthritis, very limited information regarding the event has been provided at this time. Further information is not expected.   This case was linked to MOD-2021-027371, MOD-2021-027371 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 16-Jul-2021: Follow-up information was received. New event updated and case upgraded to serious.; Sender's Comments: Based on the current available information and temporal association between the use of the product and the start date of the events, except Rheumatoid arthritis, a causal relationship cannot be excluded. Concerning the event Rheumatoid arthritis, very limited information regarding the event has been provided at this time. Further information is not expected.