POTS Syndrome after 2nd dose; Could not breath while walking after 2nd dose; Did not make it walking to the end of the hallway after 2nd dose; Passed out again after 2nd dose; Wearing a heart monitor after 2nd dose; Passed out after 2nd dose; Sternum hurting after 2nd dose; Thinks had chest pain after 2nd dose; Fatigue after 2nd dose,Very tired fast if works; Hard time breathing,Out of breath fast if works; Could not work for months after after 2nd dose; This spontaneous case was reported by a consumer and describes the occurrence of POSTURAL ORTHOSTATIC TACHYCARDIA SYNDROME (POTS Syndrome after 2nd dose), DYSPNOEA (Could not breath while walking after 2nd dose), GAIT DISTURBANCE (Did not make it walking to the end of the hallway after 2nd dose), LOSS OF CONSCIOUSNESS (Passed out after 2nd dose) and LOSS OF CONSCIOUSNESS (Passed out again after 2nd dose) in a 54-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 030B20A and 014M20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Cardiopulmonary resuscitation and Gastrointestinal surgery. Concurrent medical conditions included Autoimmune disorder and Chest pain. Concomitant products included OMALIZUMAB (XOLAIR) for an unknown indication.   On 04-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 06-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 16-Apr-2021, the patient experienced DYSPNOEA (Hard time breathing,Out of breath fast if works), LOSS OF PERSONAL INDEPENDENCE IN DAILY ACTIVITIES (Could not work for months after after 2nd dose), CHEST PAIN (Thinks had chest pain after 2nd dose) and FATIGUE (Fatigue after 2nd dose,Very tired fast if works). In July 2021, the patient experienced LOSS OF CONSCIOUSNESS (Passed out after 2nd dose) (seriousness criterion medically significant) and CHEST PAIN (Sternum hurting after 2nd dose). In August 2021, the patient experienced POSTURAL ORTHOSTATIC TACHYCARDIA SYNDROME (POTS Syndrome after 2nd dose) (seriousness criterion hospitalization), DYSPNOEA (Could not breath while walking after 2nd dose) (seriousness criterion hospitalization), GAIT DISTURBANCE (Did not make it walking to the end of the hallway after 2nd dose) (seriousness criterion hospitalization), LOSS OF CONSCIOUSNESS (Passed out again after 2nd dose) (seriousness criterion medically significant) and CARDIAC ASSISTANCE DEVICE USER (Wearing a heart monitor after 2nd dose). The patient was hospitalized from sometime in August 2021 to sometime in August 2021 due to DYSPNOEA, GAIT DISTURBANCE and POSTURAL ORTHOSTATIC TACHYCARDIA SYNDROME. At the time of the report, POSTURAL ORTHOSTATIC TACHYCARDIA SYNDROME (POTS Syndrome after 2nd dose), DYSPNOEA (Could not breath while walking after 2nd dose), GAIT DISTURBANCE (Did not make it walking to the end of the hallway after 2nd dose), LOSS OF CONSCIOUSNESS (Passed out after 2nd dose), LOSS OF CONSCIOUSNESS (Passed out again after 2nd dose), DYSPNOEA (Hard time breathing,Out of breath fast if works), LOSS OF PERSONAL INDEPENDENCE IN DAILY ACTIVITIES (Could not work for months after after 2nd dose), CHEST PAIN (Sternum hurting after 2nd dose), CARDIAC ASSISTANCE DEVICE USER (Wearing a heart monitor after 2nd dose), CHEST PAIN (Thinks had chest pain after 2nd dose) and FATIGUE (Fatigue after 2nd dose,Very tired fast if works) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In August 2021, Electrocardiogram: abnormal (abnormal) Abnormal.         Patient thought the breathing difficulty was due to her allergies. Patient was not admitted, but she was in the ER for 3 days. Treatment medications were not reported.  Company comment: The case concerns a  54-year-old-female patient with previous relevant medical history of cardiopulmonary resuscitation, who experienced the unexpected event of postural orthostatic tachycardia syndrome, dyspnoea, gait disturbance and loss of consciousness. The events occurred approximately 4 months after the second dose of Spikevax. The rechallenge was not applicable since the events have not been reported after the first dose. The benefit-risk relationship of Spikevax is not affected by this report.   This case was linked to MOD-2021-320279 (Patient Link).; Sender's Comments: The case concerns a  54-year-old-female patient with previous relevant medical history of cardiopulmonary resuscitation, who experienced the unexpected event of postural orthostatic tachycardia syndrome, dyspnoea, gait disturbance and loss of consciousness. The events occurred approximately 4 months after the second dose of Spikevax. The rechallenge was not applicable since the events have not been reported after the first dose. The benefit-risk relationship of Spikevax is not affected by this report.