Hallucinations; STOPPED BREATHING; Drug interaction; Arm infection; Sleeplessness; Memory loss; Unable to walk; This spontaneous case was reported by a physician and describes the occurrence of RESPIRATORY ARREST (STOPPED BREATHING) and HALLUCINATION (Hallucinations) in a 70-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 043B21A and 018B21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.    Co-suspect products included non-company products CARBIDOPA, LEVODOPA (DUOPA) suspension for Parkinson's disease and AMANTADINE HYDROCHLORIDE (GOCOVRI) capsule for an unknown indication.    The patient's past medical history included Non-smoker since an unknown date and Abstains from alcohol since an unknown date. Concurrent medical conditions included Drug allergy (SULFA DRUGS MANIFESTED BY SWELLING). Concomitant products included ALPRAZOLAM (XANAX) for Anxiety, MORNIFLUMATE (FLOMAX [MORNIFLUMATE]) for Catheter removal, ZOLPIDEM TARTRATE for Sleepiness, CYANOCOBALAMIN (VITAMIN B12 [CYANOCOBALAMIN]) and VITAMIN D NOS for Supplementation therapy, LEVOTHYROXINE SODIUM (SYNTHROID) for Thyroidectomy, CARBIDOPA;LEVODOPA, LEVOTHYROXINE, PARACETAMOL (TYLENOL) and CARMELLOSE SODIUM (THERA TEARS) for an unknown indication.   On 23-Sep-2017, the patient started CARBIDOPA, LEVODOPA (DUOPA) (Percutaneous) 1 dosage form. In 2018, CARBIDOPA, LEVODOPA (DUOPA) (Percutaneous) dosage was changed to dosage form. In 2020, the patient started AMANTADINE HYDROCHLORIDE (GOCOVRI) (Oral) 274 mg once a day. On 26-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 23-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. In April 2021, the patient experienced RESPIRATORY ARREST (STOPPED BREATHING) (seriousness criteria hospitalization and medically significant) and GAIT INABILITY (Unable to walk). On 23-Apr-2021, the patient experienced HALLUCINATION (Hallucinations) (seriousness criteria hospitalization and medically significant) and AMNESIA (Memory loss). On 28-Apr-2021, the patient experienced INSOMNIA (Sleeplessness). On 01-May-2021, the patient experienced LOCALISED INFECTION (Arm infection). On an unknown date, the patient experienced DRUG INTERACTION (Drug interaction). The patient was hospitalized on 28-Apr-2021 due to HALLUCINATION, and then for 12 days due to RESPIRATORY ARREST. In April 2021, RESPIRATORY ARREST (STOPPED BREATHING) had resolved. On 28-Apr-2021, GAIT INABILITY (Unable to walk) had resolved. On 03-May-2021, HALLUCINATION (Hallucinations) and INSOMNIA (Sleeplessness) had resolved. In May 2021, LOCALISED INFECTION (Arm infection) had resolved. At the time of the report, AMNESIA (Memory loss) had not resolved and DRUG INTERACTION (Drug interaction) outcome was unknown.        For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter considered RESPIRATORY ARREST (STOPPED BREATHING), HALLUCINATION (Hallucinations), GAIT INABILITY (Unable to walk), INSOMNIA (Sleeplessness) and AMNESIA (Memory loss) to be probably related and LOCALISED INFECTION (Arm infection) to be not related. No further causality assessment was provided for DRUG INTERACTION (Drug interaction).    Whilst hospitalized, unknown labs and diagnostic tests were performed with normal results. The patient was treated with unknown antibiotic intravenously during the hospitalization to treat infection in the left arm caused by the intravenous line.  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.   Most recent FOLLOW-UP information incorporated above includes: On 25-May-2021: Initial additional included patient demographics, medical history, new event information, reporter opinion of causality, suspect drug information, concomitant drug information and narrative description.; 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.