Like if it was to give a small stroke; Arrhythmia atrial; Felt without breath/something atrial, appeared something strange; Tachycardia; Arm itches and the back; Pressure was almost 200; Fatigued; Headache; reports that experienced an allergic reaction to the first dose on Aug 19th; This spontaneous case was reported by a consumer and describes the occurrence of FEELING ABNORMAL (Like if it was to give a small stroke), ARRHYTHMIA SUPRAVENTRICULAR (Arrhythmia atrial), DYSPNOEA (Felt without breath/something atrial, appeared something strange), TACHYCARDIA (Tachycardia) and PRURITUS (Arm itches and the back) in a 51-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 052E21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No Medical History information was reported.    On 19-Aug-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 19-Aug-2021, the patient experienced ARRHYTHMIA SUPRAVENTRICULAR (Arrhythmia atrial), DYSPNOEA (Felt without breath/something atrial, appeared something strange), TACHYCARDIA (Tachycardia), PRURITUS (Arm itches and the back), BLOOD PRESSURE INCREASED (Pressure was almost 200), FATIGUE (Fatigued), HEADACHE (Headache) and ALLERGY TO VACCINE (reports that experienced an allergic reaction to the first dose on Aug 19th). On an unknown date, the patient experienced FEELING ABNORMAL (Like if it was to give a small stroke). The patient was treated with OXYGEN for Adverse event, at an unspecified dose and frequency. At the time of the report, FEELING ABNORMAL (Like if it was to give a small stroke), ARRHYTHMIA SUPRAVENTRICULAR (Arrhythmia atrial), DYSPNOEA (Felt without breath/something atrial, appeared something strange), TACHYCARDIA (Tachycardia), PRURITUS (Arm itches and the back), BLOOD PRESSURE INCREASED (Pressure was almost 200), FATIGUE (Fatigued), HEADACHE (Headache) and ALLERGY TO VACCINE (reports that experienced an allergic reaction to the first dose on Aug 19th) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 19-Aug-2021, Blood pressure measurement: 200 (High) Pressure was almost 200 and had tachycardia. On 19-Aug-2021, Chest X-ray: normal (normal) Thorax X ray and was fine.. On 19-Aug-2021, Electrocardiogram: normal (normal) ECG that resulted fine.The patient mentioned that had tachycardia. On an unknown date, Blood pressure measurement: 180 (High) pressure went up to 180.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was unknown.       Concomitant product use was not provided by the reporter.  Treatment information was recived oxygen after 45 minutes and blood pressure sub lingual pill.; Sender's Comments: This case concerns a 51-year-old, female patient with no relevant medical history, who experienced the unexpected events of arrhythmia supraventricular, dyspnoea, blood pressure increased, tachycardia, feeling abnormal, pruritus and the expected events of allergy to vaccine, fatigue and headache. The events occurred the same day after the first dose of Spikevax. The rechallenge was not applicable, as the events happened after the first dose. The benefit-risk relationship of Spikevax is not affected by this report.