severe joint pain in his body; could hardly walk; pain and inflammation progressed into his hands, knees, lower back, hips and ankles.; inflammation progressed into his hands, knees, lower back, hips and ankles/ inflammation came back; both hands had swollen up; lost weight/ weight dropped down to 171 lbs.; This spontaneous case was reported by a consumer and describes the occurrence of ARTHRALGIA (severe joint pain in his body), GAIT DISTURBANCE (could hardly walk), PAIN (pain and inflammation progressed into his hands, knees, lower back, hips and ankles.), INFLAMMATION (inflammation progressed into his hands, knees, lower back, hips and ankles/ inflammation came back), PERIPHERAL SWELLING (both hands had swollen up) and WEIGHT DECREASED (lost weight/ weight dropped down to 171 lbs.) in a 68-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     The patient's past medical history included Meniscus of knee removal in March 2021.   On 18-Jan-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 18-Feb-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. In March 2021, the patient experienced WEIGHT DECREASED (lost weight/ weight dropped down to 171 lbs.) (seriousness criterion medically significant). On an unknown date, the patient experienced ARTHRALGIA (severe joint pain in his body) (seriousness criterion medically significant), GAIT DISTURBANCE (could hardly walk) (seriousness criterion medically significant), PAIN (pain and inflammation progressed into his hands, knees, lower back, hips and ankles.) (seriousness criterion medically significant), INFLAMMATION (inflammation progressed into his hands, knees, lower back, hips and ankles/ inflammation came back) (seriousness criterion medically significant) and PERIPHERAL SWELLING (both hands had swollen up) (seriousness criterion medically significant). The patient was treated with PREDNISONE for Antiinflammatory therapy, at a dose of 40 mg once a day. At the time of the report, ARTHRALGIA (severe joint pain in his body), GAIT DISTURBANCE (could hardly walk), PAIN (pain and inflammation progressed into his hands, knees, lower back, hips and ankles.), INFLAMMATION (inflammation progressed into his hands, knees, lower back, hips and ankles/ inflammation came back) and PERIPHERAL SWELLING (both hands had swollen up) outcome was unknown and WEIGHT DECREASED (lost weight/ weight dropped down to 171 lbs.) was resolving.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In March 2021, Weight decreased: low (Low) weight dropped down to 171 lbs in March and April 2021. In 2021, Inflammatory marker test: 174 (High) 174..         Concomitant product use was not provided by the reporter.  Treatment medication include unknown anti-inflammatory medication. On unknown date, the patient had an additional test performed that included a cancer test, liver test, colonoscopy, CAT Scan of lungs, however, the result was normal provided. reported that the pain and inflammation progressed into his hands, knees, lower back, hips and ankles stated he thought the medications he was prescribed got everything under control and discontinued the medications in July 2021. He reported that the inflammation came back, and he had to go back on Prednisone treatment.  Company Comment: This case concerns a 68-year-old, male patient with no relevant medical history who experienced the unexpected and serious events of arthralgia, gait disturbance, pain, inflammation, weight decreased and peripheral swelling. The events occurred after the second dose of Moderna COVID vaccine was administered (exact dates unknown). The rechallenge was not applicable as the event happened after the second dose. The benefit-risk relationship of Moderna COVID vaccine is not affected by this report.   This case was linked to MOD-2021-331123 (Patient Link).; Sender's Comments: This case concerns a 68-year-old, male patient with no relevant medical history who experienced the unexpected and serious events of arthralgia, gait disturbance, pain, inflammation, weight decreased and peripheral swelling. The events occurred after the second dose of Moderna COVID vaccine was administered (exact dates unknown). The rechallenge was not applicable as the event happened after the second dose. The benefit-risk relationship of Moderna COVID vaccine is not affected by this report.