Encephalopathy; Pneumonia; Hypoxia; Unresponsive to stimuli; Mental status changes; This case was received via FDA VAERS (Reference number: 1182714) on 11-May-2021 and was forwarded to Moderna on 11-May-2021.    This regulatory authority case was reported by an other health care professional and describes the occurrence of ENCEPHALOPATHY (Encephalopathy), PNEUMONIA (Pneumonia), HYPOXIA (Hypoxia), UNRESPONSIVE TO STIMULI (Unresponsive to stimuli) and MENTAL STATUS CHANGES (Mental status changes) in a 66-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 030A21A) for COVID-19 vaccination.     Concurrent medical conditions included Epilepsy, Dementia, Hypertension, Diabetes and Benign prostatic hyperplasia. Concomitant products included AMLODIPINE, ASPIRIN [ACETYLSALICYLIC ACID], ATORVASTATIN, CALCIUM CARBONATE, ERGOCALCIFEROL (CALCIUM/VITAMIN D [CALCIUM CARBONATE;ERGOCALCIFEROL]), CARBAMAZEPINE, CARVEDILOL, DONEPEZIL, FINASTERIDE, GABAPENTIN, HALOPERIDOL, HYDRALAZINE, INSULIN, LEVETIRACETAM, LISINOPRIL, OXYBUTYNIN, POLYETHYLENE GLYCOL 3350, TAMSULOSIN and SENNA ALEXANDRINA EXTRACT (SENNALAX [SENNA ALEXANDRINA EXTRACT]) for an unknown indication.   On 02-Mar-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On an unknown date, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 16-Mar-2021, the patient experienced ENCEPHALOPATHY (Encephalopathy) (seriousness criteria hospitalization, medically significant and life threatening), PNEUMONIA (Pneumonia) (seriousness criteria hospitalization, medically significant and life threatening), HYPOXIA (Hypoxia) (seriousness criteria hospitalization, medically significant and life threatening), UNRESPONSIVE TO STIMULI (Unresponsive to stimuli) (seriousness criteria hospitalization, medically significant and life threatening) and MENTAL STATUS CHANGES (Mental status changes) (seriousness criteria hospitalization and life threatening). At the time of the report, ENCEPHALOPATHY (Encephalopathy), PNEUMONIA (Pneumonia), HYPOXIA (Hypoxia), UNRESPONSIVE TO STIMULI (Unresponsive to stimuli) and MENTAL STATUS CHANGES (Mental status changes) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 16-Mar-2021, Blood glucose: normal (normal) normal and 172 172. On 16-Mar-2021, Blood pressure measurement: 130/78 130/78. On 16-Mar-2021, Body temperature: 101.7 (High) 101.7. On 16-Mar-2021, Heart rate: 104 104. On 16-Mar-2021, Oxygen saturation: 95 % 95. On 16-Mar-2021, SARS-CoV-2 test: negative (Negative) Negative.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   No treatment drug information was provided.  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.; 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.