Fainted; Stopped breathing; Abdominal pain; Began to feel ligh headed; Metallic taste in mouth; I was very Hot & sweaty; I was very Hot & sweaty; I had been dreaming; I became very nauseated & thought i was going to throw up; I was very weak & unable to feel better; My face was all red & splotchy; This spontaneous case was reported by an other health care professional and describes the occurrence of SYNCOPE (Fainted), RESPIRATORY ARREST (Stopped breathing), ABDOMINAL PAIN (Abdominal pain), DIZZINESS (Began to feel ligh headed), DYSGEUSIA (Metallic taste in mouth), FEELING HOT (I was very Hot & sweaty), HYPERHIDROSIS (I was very Hot & sweaty), ABNORMAL DREAMS (I had been dreaming), NAUSEA (I became very nauseated & thought i was going to throw up), ASTHENIA (I was very weak & unable to feel better) and ERYTHEMA (My face was all red & splotchy) in a 28-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 042B212A) for COVID-19 vaccination.     No Medical History information was reported.    On 20-Jul-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 20-Jul-2021, the patient experienced SYNCOPE (Fainted) (seriousness criteria hospitalization and medically significant), RESPIRATORY ARREST (Stopped breathing) (seriousness criteria hospitalization and medically significant), ABDOMINAL PAIN (Abdominal pain) (seriousness criterion hospitalization), DYSGEUSIA (Metallic taste in mouth) (seriousness criterion hospitalization), FEELING HOT (I was very Hot & sweaty) (seriousness criterion hospitalization), HYPERHIDROSIS (I was very Hot & sweaty) (seriousness criterion hospitalization), ABNORMAL DREAMS (I had been dreaming) (seriousness criterion hospitalization), NAUSEA (I became very nauseated & thought i was going to throw up) (seriousness criterion hospitalization), ASTHENIA (I was very weak & unable to feel better) (seriousness criterion hospitalization) and ERYTHEMA (My face was all red & splotchy) (seriousness criterion hospitalization). 20-Jul-2021, the patient experienced DIZZINESS (Began to feel ligh headed) (seriousness criterion hospitalization). The patient was hospitalized on 20-Jul-2021 due to ABDOMINAL PAIN, ABNORMAL DREAMS, ASTHENIA, DIZZINESS, DYSGEUSIA, ERYTHEMA, FEELING HOT, HYPERHIDROSIS, NAUSEA, RESPIRATORY ARREST and SYNCOPE. The patient was treated with DIPHENHYDRAMINE HYDROCHLORIDE (BENADRYL [DIPHENHYDRAMINE HYDROCHLORIDE]) on 20-Jul-2021 for Red face, at an unspecified dose and frequency. On 20-Jul-2021, SYNCOPE (Fainted) had resolved. At the time of the report, RESPIRATORY ARREST (Stopped breathing), ABDOMINAL PAIN (Abdominal pain), DIZZINESS (Began to feel ligh headed), DYSGEUSIA (Metallic taste in mouth), FEELING HOT (I was very Hot & sweaty), HYPERHIDROSIS (I was very Hot & sweaty), ABNORMAL DREAMS (I had been dreaming), NAUSEA (I became very nauseated & thought i was going to throw up), ASTHENIA (I was very weak & unable to feel better) and ERYTHEMA (My face was all red & splotchy) outcome was unknown.        The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   No Medical History information was reported.  Concomitant medications were not provided.  No treatment medications were provided.  It was reported that the patient was observe at hospital for about 5 hours.  Company 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.   Most recent FOLLOW-UP information incorporated above includes: On 18-Aug-2021: Significant follow-up received on 18-Aug-2021: contains Events added, upgraded to serious, Facility information 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