Feels very sick; Loss of balance; Unconscious again; On same day in the evening, he blacked out/He sat down because he lost his balance; Migraine; Numb/He was numb on both sides of body/Left side numbness was worst than right side; He was sweating.; He was dehydrated and numb.; He went pale; He didn't feel well.; He felt cold; This spontaneous case was reported by a consumer and describes the occurrence of LOSS OF CONSCIOUSNESS (Unconscious again), SYNCOPE (On same day in the evening, he blacked out/He sat down because he lost his balance), MIGRAINE (Migraine), HYPOAESTHESIA (Numb/He was numb on both sides of body/Left side numbness was worst than right side), HYPERHIDROSIS (He was sweating.), DEHYDRATION (He was dehydrated and numb.), PALLOR (He went pale), MALAISE (He didn't feel well.), NASOPHARYNGITIS (He felt cold), ILLNESS (Feels very sick) and BALANCE DISORDER (Loss of balance) in a 38-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. Unknown) for COVID-19 vaccination.     No Medical History information was reported.    On 02-Sep-2021, the patient received dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 02-Sep-2021, the patient experienced LOSS OF CONSCIOUSNESS (Unconscious again) (seriousness criteria hospitalization and medically significant), SYNCOPE (On same day in the evening, he blacked out/He sat down because he lost his balance) (seriousness criteria hospitalization and medically significant), MIGRAINE (Migraine) (seriousness criterion hospitalization), HYPOAESTHESIA (Numb/He was numb on both sides of body/Left side numbness was worst than right side) (seriousness criterion hospitalization), HYPERHIDROSIS (He was sweating.) (seriousness criterion hospitalization), DEHYDRATION (He was dehydrated and numb.) (seriousness criterion hospitalization), PALLOR (He went pale) (seriousness criterion hospitalization), MALAISE (He didn't feel well.) (seriousness criterion hospitalization) and NASOPHARYNGITIS (He felt cold) (seriousness criterion hospitalization). On an unknown date, the patient experienced ILLNESS (Feels very sick) (seriousness criterion hospitalization) and BALANCE DISORDER (Loss of balance) (seriousness criterion hospitalization). At the time of the report, LOSS OF CONSCIOUSNESS (Unconscious again), SYNCOPE (On same day in the evening, he blacked out/He sat down because he lost his balance), MIGRAINE (Migraine), HYPOAESTHESIA (Numb/He was numb on both sides of body/Left side numbness was worst than right side), HYPERHIDROSIS (He was sweating.), DEHYDRATION (He was dehydrated and numb.), PALLOR (He went pale), MALAISE (He didn't feel well.), NASOPHARYNGITIS (He felt cold), ILLNESS (Feels very sick) and BALANCE DISORDER (Loss of balance) outcome was unknown.        The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.       No concomitant medications were provided by reporter. Treatment medication provided was Oral migraine medication, IV fluids  Company Comment : Based on the current available information and highly plausible temporal association between the use of the product and the onset date of the events, a causal relationship cannot be excluded. Therefore, causality is assessed as possibly related.   Most recent FOLLOW-UP information incorporated above includes: On 08-Sep-2021: Reporter information added, Patient demographic added, Dosage date updated, Events updated , loss of consciousness, syncope, malaise, pallor, nasopharyngitis, hyperhidrosis, dehydration, hypoesthesia, migraine, illness; Sender's Comments: Based on the current available information and highly plausible temporal association between the use of the product and the onset date of the events, a causal relationship cannot be excluded. Therefore, causality is assessed as possibly related.