It doesn't feel like I'm getting better; Severe reaction; Chills; Felt light-headed; I felt like I was going to blackout which went on for 8 hours; I knew something wasn't right, my heart would go boom"; Pain; Woke up and felt like I was being strangled, it seems that in the night laying down, I have severe attacks; This spontaneous case was reported by a consumer and describes the occurrence of LOSS OF CONSCIOUSNESS (I felt like I was going to blackout which went on for 8 hours), ASPHYXIA (Woke up and felt like I was being strangled, it seems that in the night laying down, I have severe attacks), CARDIAC DISCOMFORT (I knew something wasn't right, my heart would go boom"), PAIN (Pain) and MALAISE (It doesn't feel like I'm getting better) in a 76-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 027A21A and 028A21A) 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 LEVOTHYROXINE SODIUM (SYNTHROID) and AMLODIPINE for an unknown indication.   On 02-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 01-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 03-Mar-2021, the patient experienced ASPHYXIA (Woke up and felt like I was being strangled, it seems that in the night laying down, I have severe attacks) and PAIN (Pain). On 10-Mar-2021, the patient experienced LOSS OF CONSCIOUSNESS (I felt like I was going to blackout which went on for 8 hours) and DIZZINESS (Felt light-headed). 10-Mar-2021, the patient experienced CARDIAC DISCOMFORT (I knew something wasn't right, my heart would go boom"). On an unknown date, the patient experienced MALAISE (It doesn't feel like I'm getting better), VACCINATION COMPLICATION (Severe reaction) and CHILLS (Chills). The patient was treated with DEXAMETHASONE at an unspecified dose and frequency; PARACETAMOL (TYLENOL) for Pain, at an unspecified dose and frequency; PREDNISONE for Adverse event, at a dose of 20 mg five times per week; PREDNISONE for Adverse event, at a dose of 15 mg five times per week and HYDROXYCHLOROQUINE for Adverse event, at an unspecified dose and frequency. On 10-Mar-2021, LOSS OF CONSCIOUSNESS (I felt like I was going to blackout which went on for 8 hours) had resolved. At the time of the report, ASPHYXIA (Woke up and felt like I was being strangled, it seems that in the night laying down, I have severe attacks), CARDIAC DISCOMFORT (I knew something wasn't right, my heart would go boom"), PAIN (Pain), MALAISE (It doesn't feel like I'm getting better), DIZZINESS (Felt light-headed), VACCINATION COMPLICATION (Severe reaction) and CHILLS (Chills) outcome was unknown.        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. Events Loss of Consciousness and Asphyxia were automatically upgraded as a Serious event as per IME list. However, based on information available and as per medical criteria were classified as Non-serious.   This case was linked to MOD-2021-225080 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 04-Aug-2021: Significant Follow-up Append: Batch\Lot No were 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 Events Loss of Consciousness and Asphyxia were automatically upgraded as a Serious event as per IME list. However, based on information available and as per medical criteria were classified as Non-serious.