Couldn't lift arm or get of bed; Baker's cyst; Left knee has been swollen/leg feels heavy and difficult to lift; Reactive arthritis flare; didn't receive the second dose,was advised not to; Stabbing pain in upper left arm, in the crease of arm/Stabbing pain in left elbow, right elbow, forearm, upper arm, left and right groin radiating down leg, sore arm; Excruciating joint pain; Fatigue; Severe body pain; This spontaneous case was reported by a consumer (subsequently medically confirmed) and describes the occurrence of ARTHRITIS REACTIVE (Reactive arthritis flare) in a 65-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 007M20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Streptococcal sore throat from 12-Feb-2021 to 17-Feb-2021, Shortness of breath (The patient reported no significant change in the disease condition.) in 2006, Sciatica (The patient reported a significant change in the disease condition.) in 1995 and Elbow tendinitis (The patient reported a significant change in the disease condition.) in 2017. Concurrent medical conditions included Drug allergy (Biaxin, citalopram, venlafaxine, trimethoprim, sulfamethoxazole.), Hypothyroidism (The dose is lowered from 125 mg to 112) since 1988, Asthma (The patient reported no significant change in the disease condition.) since 01-Dec-2020 and Chronic obstructive pulmonary disease (The patient reported no significant change in the disease condition.) since 01-Dec-2020. Concomitant products included OXYMETAZOLINE HYDROCHLORIDE (CLARITIN ALLERGIC) for Allergy, MONTELUKAST from 01-Nov-2020 to an unknown date for Asthma, FLUTICASONE FUROATE, VILANTEROL TRIFENATATE (BREO ELLIPTA) from 15-Jan-2021 to an unknown date for COPD and Asthma, PANTOPRAZOLE from 08-Jan-2021 to an unknown date and CIMETIDINE from 04-Jan-2021 to an unknown date for Hyperacidity, EZETIMIBE from 23-Jun-2020 to an unknown date for Hyperlipidemia, LEVOTHYROXINE SODIUM (SYNTHROID) for Hypothyroidism, PENICILLIN NOS from 12-Feb-2021 to 22-Feb-2021 for Streptococcal sore throat, BIFIDOBACTERIUM LACTIS (PROBIOTIC [BIFIDOBACTERIUM LACTIS]), CALCIUM, VITAMIN D3, VITAMIN E NOS, MAGNESIUM and VITAMIN B COMPLEX (SUPER B COMPLEX [VITAMIN B COMPLEX]) from 04-Jan-2021 to an unknown date for an unknown indication.    On 19-Feb-2021 at 8:30 AM, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 23-Feb-2021, the patient experienced PAIN (Severe body pain), ARTHRALGIA (Excruciating joint pain) and FATIGUE (Fatigue). On 24-Feb-2021, the patient experienced PAIN IN EXTREMITY (Stabbing pain in upper left arm, in the crease of arm/Stabbing pain in left elbow, right elbow, forearm, upper arm, left and right groin radiating down leg, sore arm). On 08-Apr-2021, the patient experienced PRODUCT DOSE OMISSION ISSUE (didn't receive the second dose,was advised not to). On 14-Apr-2021, the patient experienced ARTHRITIS REACTIVE (Reactive arthritis flare) (seriousness criterion medically significant) and JOINT SWELLING (Left knee has been swollen/leg feels heavy and difficult to lift). On an unknown date, the patient experienced LOSS OF PERSONAL INDEPENDENCE IN DAILY ACTIVITIES (Couldn't lift arm or get of bed) and SYNOVIAL CYST (Baker's cyst). The patient was treated with PARACETAMOL (TYLENOL) at a dose of 1 dosage form; IBUPROFEN at a dose of 1 dosage form; GABAPENTIN ongoing since an unknown date at a dose of 200 mg; CELECOXIB (CELEBREX) at a dose of 200 mg; METHYLPREDNISOLONE ongoing since an unknown date at a dose of 4 mg; METHOCARBAMOL ongoing since an unknown date at a dose of 750 mg as required; FERUMOXYTOL (FERAHEME) ongoing from 06-May-2021 at a dose of 1 dosage form, first infusion; FERUMOXYTOL (FERAHEME) on 13-May-2021 at a dose of 1 dosage form, second infusion and CORTISONE ongoing since an unknown date at a dose of 1 dosage form. On 08-Apr-2021, PRODUCT DOSE OMISSION ISSUE (didn't receive the second dose,was advised not to) had resolved. At the time of the report, ARTHRITIS REACTIVE (Reactive arthritis flare), PAIN (Severe body pain), LOSS OF PERSONAL INDEPENDENCE IN DAILY ACTIVITIES (Couldn't lift arm or get of bed), SYNOVIAL CYST (Baker's cyst), JOINT SWELLING (Left knee has been swollen/leg feels heavy and difficult to lift), PAIN IN EXTREMITY (Stabbing pain in upper left arm, in the crease of arm/Stabbing pain in left elbow, right elbow, forearm, upper arm, left and right groin radiating down leg, sore arm), ARTHRALGIA (Excruciating joint pain) and FATIGUE (Fatigue) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 08-Mar-2021, Blood albumin (3.8-4.8): 3.7 (normal) 3.7g/dL. On 08-Mar-2021, Blood cholesterol: 172 (normal) 172 mg/dl. On 08-Mar-2021, Blood glucose (65-99): 88 (normal) 88mg/dl. On 08-Mar-2021, Blood iron (45-160): 39 (Low) Low. On 08-Mar-2021, Eosinophil count (15-500): 1003 (High) 1003 cells per microlitre. On 08-Mar-2021, Glycosylated haemoglobin increased: 6.0 (High) Unknown. On 08-Mar-2021, Haematocrit: 33.9 (Low) 33.9 %. On 08-Mar-2021, Haemoglobin (11.7-15.5): 10.6 (Low) unknown. On 08-Mar-2021, Mean cell haemoglobin (27.0-33.0): 25.2 (Low) unknown. On 08-Mar-2021, Mean cell haemoglobin concentration (32.0-36.0): 31.3 (Low) Unknown. On 08-Mar-2021, Platelet count (140-400): 396 (normal) Unknown. On 08-Mar-2021, Protein total (6.1-8.1): 5.7 normal. On 08-Mar-2021, Prothrombin time (9.1-1.2): 9.8 (normal) Unknown. On 08-Mar-2021, Red blood cell count (3.80-5.10): 4.21 (normal) unknown. On 08-Mar-2021, Red cell distribution width increased (11.0-15.0): 15.2 (High) Unknown. On 08-Mar-2021, Serum ferritin (16-288): 6 (Low) Unknown. On 08-Mar-2021, Thyroid function test: negative (Negative) thyroid was off.. On 08-Mar-2021, White blood cell count (3.8-10.8): 7.6 (normal) unknown. On 19-Mar-2021, SARS-CoV-2 test: negative (Negative) Negative. On 14-Apr-2021, Magnetic resonance imaging: unknown (Inconclusive) Bakers cyst and fluid on knee. On 26-Apr-2021, X-ray: unknown (Inconclusive) Left knee x-ray: Moderate joint effusion. On 10-May-2021, Magnetic resonance imaging: unknown (Inconclusive) Mild hand subcutaneous edema and unknown (Inconclusive) Mild diffuse flexor tenosynovitis from CMC joint level to metacarpal midshaft level. On 12-May-2021, Blood albumin (3.8-4.8): 3.6 (Low) 3.6g/dL. On 12-May-2021, C-reactive protein: 27.5 (High) Unknown. On 12-May-2021, Eosinophil count (15-500): 57 (normal) 57 cells per microlitre. On 12-May-2021, Haematocrit: 37.8 (normal) 37.8%. On 12-May-2021, Haemoglobin (11.7-15.5): 11.9 (normal) Unknown. On 12-May-2021, Mean cell haemoglobin (27.0-33.0): 25.4 (Low) Unknown. On 12-May-2021, Mean cell haemoglobin concentration (32.0-36.0): 31.5 (Low) Unknown. On 12-May-2021, Platelet count (140-400): 458 (High) Unknown. On 12-May-2021, Protein total (6.1-8.1): 6.6 (normal) Unknown. On 12-May-2021, Red blood cell count (3.80-5.10): 4.69 (normal) Unknown. On 12-May-2021, Red cell distribution width increased (11.0-15.0): 16.5 (High) Unknown. On 12-May-2021, White blood cell count (3.8-10.8): 8.1 (normal) Unknown.     mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was withdrawn on an unknown date.       The patient reported that she declined the administration of second dose and it was suggested by her physician.  For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.  Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded. This report refers to a case of Product dose omission issue for mRNA-1273, lot # 007M20A with associated AEs.   Most recent FOLLOW-UP information incorporated above includes: On 17-May-2021: Follow up received on 17-May-2021 and does not contain any new information On 21-May-2021: The second follow up received on 21-MAY-2021 and contain contact details of the reporter . The suspect drug dosage regime, medical history and events of the patient is updated.The concomitant and treatment medications are added.; 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, a causal relationship cannot be excluded. This report refers to a case of Product dose omission issue for mRNA-1273, lot # 007M20A with associated AEs.