Swelling in her left knee more than the right knee/The swelling extends to her left ankle and to halfway up her left hip.; difficult and painful to walk as well as bend; both legs swollen and painful; Both legs swollen and painful/Left leg worse than right leg; left knee pain behind the knee, side of knee/Pain spread to left ankle and part 1/2 of thigh; Body aches - shoulder and neck; Fever; Chills; This spontaneous case was reported by a consumer and describes the occurrence of PERIPHERAL SWELLING (both legs swollen and painful), PAIN IN EXTREMITY (Both legs swollen and painful/Left leg worse than right leg), JOINT SWELLING (Swelling in her left knee more than the right knee/The swelling extends to her left ankle and to halfway up her left hip.), MOBILITY DECREASED (difficult and painful to walk as well as bend) and MYALGIA (Body aches - shoulder and neck) in a 54-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 038C21A and lot# 007C211A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No medical history was provided by the reporter.  Concomitant products included ENALAPRIL, HYDROCHLOROTHIAZIDE and CARVEDILOL for Hypertension, METHADONE and OXYCODONE HYDROCHLORIDE, OXYCODONE TEREPHTHALATE, PARACETAMOL (PERCOCET [OXYCODONE HYDROCHLORIDE;OXYCODONE TEREPHTHALATE;PARACETAMOL]) for Pain, ACETYLSALICYLIC ACID (ASPIRIN (E.C.)), ESTRADIOL, MIRTAZAPINE (REMERON), ALPRAZOLAM, ZOLPIDEM TARTRATE (AMBIEN) and SALBUTAMOL SULFATE (VENTOLIN HFA) for an unknown indication.   On 26-Apr-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 24-May-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 29-May-2021, the patient experienced MYALGIA (Body aches - shoulder and neck), PYREXIA (Fever) and CHILLS (Chills). On 02-Jun-2021, the patient experienced PERIPHERAL SWELLING (both legs swollen and painful), PAIN IN EXTREMITY (Both legs swollen and painful/Left leg worse than right leg) and ARTHRALGIA (left knee pain behind the knee, side of knee/Pain spread to left ankle and part 1/2 of thigh). On an unknown date, the patient experienced JOINT SWELLING (Swelling in her left knee more than the right knee/The swelling extends to her left ankle and to halfway up her left hip.) and MOBILITY DECREASED (difficult and painful to walk as well as bend). The patient was treated with IBUPROFEN for Pain, at a dose of 800 milligram three times a day; METHADONE for Pain, at a dose of 10 milligram three times a day; OXYCODONE HYDROCHLORIDE, OXYCODONE TEREPHTHALATE, PARACETAMOL (PERCOCET [OXYCODONE HYDROCHLORIDE;OXYCODONE TEREPHTHALATE;PARACETAMOL]) ongoing since an unknown date for Pain, at an unspecified dose and frequency and PREDNISONE ongoing since an unknown date for Pain, at an unspecified dose and frequency. On 01-Jun-2021, MYALGIA (Body aches - shoulder and neck), PYREXIA (Fever) and CHILLS (Chills) had resolved. At the time of the report, PERIPHERAL SWELLING (both legs swollen and painful), PAIN IN EXTREMITY (Both legs swollen and painful/Left leg worse than right leg), JOINT SWELLING (Swelling in her left knee more than the right knee/The swelling extends to her left ankle and to halfway up her left hip.), MOBILITY DECREASED (difficult and painful to walk as well as bend) and ARTHRALGIA (left knee pain behind the knee, side of knee/Pain spread to left ankle and part 1/2 of thigh) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Pain assessment (1-10): 3-4 Pain in right knee 3-4/10 and 7-8 Pain in left knee is 7-8/10.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   Patient stated that the steroid helped a little but the pain was persistent then. She called her primary care physician's office and spoke to the nurse practitioner who advised her to go to the ER. Action taken with Covid-19 vaccine (mRNA-1273) was not applicable.   This case was linked to MOD-2021-213290 (Patient Link).