Mostly in my back and knees; when I get up and do things, I have to try and pace myself/in walking, I have to go real slow; Sometimes my hips and thighs; when it's in my joints, I usually take something and it would relieve the pain for a little while/ mostly in my back and knees; The muscle pain got pretty bad/mostly muscle pain that I'm experiencing after the vaccine/I still have it / its never in the same place; This case was received via an unknown source (no reference has been entered for a health authority or license partner) on 17-Sep-2021 and was forwarded to Moderna on 17-Sep-2021.    This spontaneous case was reported by a consumer and describes the occurrence of BACK PAIN (Mostly in my back and knees), GAIT DISTURBANCE (when I get up and do things, I have to try and pace myself/in walking, I have to go real slow), PAIN IN EXTREMITY (Sometimes my hips and thighs), ARTHRALGIA (when it's in my joints, I usually take something and it would relieve the pain for a little while/ mostly in my back and knees) and MYALGIA (The muscle pain got pretty bad/mostly muscle pain that I'm experiencing after the vaccine/I still have it / its never in the same place) in a 66-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 013M201A and 011L20A) for COVID-19 vaccination.     The patient's past medical history included Rheumatoid arthritis. Concomitant products included CERTOLIZUMAB PEGOL (CIMZIA) for Arthritis, MULTI VITAMIN & MINERAL, FOLIC ACID, GABAPENTIN, HYDROCHLOROTHIAZIDE, LEFLUNOMIDE, LEVOTHYROXINE SODIUM, LOSARTAN POTASSIUM, METOPROLOL TARTRATE, FLUOXETINE HYDROCHLORIDE (FLUOXETINE HCL), ROSUVASTATIN CALCIUM and COLECALCIFEROL (VITAMIN D3) for an unknown indication.   On 09-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 09-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 14-Mar-2021, the patient experienced MYALGIA (The muscle pain got pretty bad/mostly muscle pain that I'm experiencing after the vaccine/I still have it / its never in the same place). On an unknown date, the patient experienced BACK PAIN (Mostly in my back and knees), GAIT DISTURBANCE (when I get up and do things, I have to try and pace myself/in walking, I have to go real slow), PAIN IN EXTREMITY (Sometimes my hips and thighs) and ARTHRALGIA (when it's in my joints, I usually take something and it would relieve the pain for a little while/ mostly in my back and knees). The patient was treated with NAPROXEN SODIUM (ALEVE) at a dose of Unknown and NAPROXEN SODIUM (ALEVE BACK & MUSCLE PAIN) at an unspecified dose and frequency. At the time of the report, BACK PAIN (Mostly in my back and knees), GAIT DISTURBANCE (when I get up and do things, I have to try and pace myself/in walking, I have to go real slow), PAIN IN EXTREMITY (Sometimes my hips and thighs), ARTHRALGIA (when it's in my joints, I usually take something and it would relieve the pain for a little while/ mostly in my back and knees) and MYALGIA (The muscle pain got pretty bad/mostly muscle pain that I'm experiencing after the vaccine/I still have it / its never in the same place) had not resolved.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   Patient took Bayer back and body as treatment.