Asthenia; Chills; Gait disturbance; Pyrexia; This case was received via FDA VAERS on 25-May-2021 and was forwarded to Moderna on 25-May-2021.    This regulatory authority case was reported by an other health care professional and describes the occurrence of ASTHENIA (Asthenia), CHILLS (Chills), GAIT DISTURBANCE (Gait disturbance) and PYREXIA (Pyrexia) in a 71-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.     Concurrent medical conditions included Drug allergy (Cefaclor - severe swelling/hives), Arthritis, Cancer (Non-Hodgkin's last chemo 12/26/18), Congestive heart failure, COPD, Coronary artery disease, Dementia, Depression, Diabetes mellitus, Hypertension, Kidney stone and Urinary tract infection. Concomitant products included SACUBITRIL VALSARTAN SODIUM HYDRATE (ENTRESTO) for Congestive heart failure, DONEPEZIL for Dementia, SERTRALINE for Depression, INSULIN ASPART, METFORMIN, INSULIN DEGLUDEC and DULAGLUTIDE for Diabetes, APIXABAN (APIXABAN ACCORD), MAGNESIUM OXIDE, LORATADINE, SPIRONOLACTONE, TORSEMIDE, ASPIRIN [ACETYLSALICYLIC ACID], OXYCODONE HYDROCHLORIDE, PARACETAMOL (OXYCODONE/APAP [OXYCODONE HYDROCHLORIDE;PARACETAMOL]), FESOTERODINE and CHOLECALCIFEROL for an unknown indication.    On 06-Apr-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 07-Apr-2021, the patient experienced ASTHENIA (Asthenia) (seriousness criterion hospitalization) and GAIT DISTURBANCE (Gait disturbance) (seriousness criterion hospitalization). 07-Apr-2021, the patient experienced CHILLS (Chills) (seriousness criterion hospitalization) and PYREXIA (Pyrexia) (seriousness criterion hospitalization). The patient was treated with ASPIRIN [ACETYLSALICYLIC ACID] for Symptomatic treatment, at a dose of 1 UNK and MORPHINE for Symptomatic treatment, at an unspecified dose and frequency. At the time of the report, ASTHENIA (Asthenia), CHILLS (Chills), GAIT DISTURBANCE (Gait disturbance) and PYREXIA (Pyrexia) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 07-Apr-2021, Body temperature: 100.1 (High) Fever of 100.1. On 07-Apr-2021, Chest X-ray: normal (normal) Chest X-ray-normal.. On 07-Apr-2021, Troponin: increased (High) Troponin level was slightly above the reference range however he has had elevated troponin in the past..     For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   Patient was on anticoagulant therapy in past and also wears life vest since MAR-2019. Patient experienced fever and chills after receiving second dose of vaccine, then he went to the emergency department on 08-APR-2021. Patient denied any cough, nausea, vomiting, diarrhea, chest pain, shortness of breath or other symptoms. Patient was triaged in the emergency room. Patient's labs were within normal limits and his chest x-ray was negative for any acute infection. Patient's troponin in the lab was slightly above the reference range however he has had elevated troponins in the past. Patient was given ASA and Morphine for the treatment in the emergency room. Patient was discharged from the emergency room but was so weak that he was unable to ambulate to his car, so was admitted for overnight stay/observation. In the hospital, patient's continued his home meds and was discharged on 08-APR-2021.  Company Comment: 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.  Nevertheless, patient current medical conditions and concomitant medications could be potentially confounders/co-suspects; 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.  Nevertheless, patient current medical conditions and concomitant medications could be potentially confounders/co-suspects