2 days after receiving the last booster I suffered a series of fainting spells; slightly enlarged heard; first degree AV block; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 67-year-old female patient (not pregnant) received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), on 12Dec2022 at 15:00 as (dose 5 (booster), single) (Lot number: GL0446) at the age of 67 years, in left arm for covid-19 immunisation. The patient's relevant medical history included: "Allergy" (unspecified if ongoing). There were no concomitant medications. Vaccination history included: BNT162b2 (Dose Number: 4, Batch/Lot No: FN2908, Location of injection: Arm Left, Vaccine Administration Time: 03:30 PM), administration date: 06Jun2022, when the patient was 66-year-old, for COVID-19 immunization, reaction(s): "some slight dizziness", "fluttering in my chest"; BNT162b2 (Dose Number: 3, Batch/Lot No: FF2590, Location of injection: Arm Left, Vaccine Administration Time: 09:15 AM), administration date: 09Nov2021, when the patient was 66-year-old, for COVID-19 immunization, reaction(s): "some slight dizziness", "fluttering in my chest"; BNT162b2 (Dose Number: 2, Batch/Lot No: EN6203, Location of injection: Arm Left, Vaccine Administration Time: 08:30 AM), administration date: 24Mar2021, when the patient was 65-year-old, for COVID-19 immunization, reaction(s): "some slight dizziness", "fluttering in my chest"; BNT162b2 (Dose Number: 1, Batch/Lot No: EN6196, Location of injection: Arm Left, Vaccine Administration Time: 12:00 AM), administration date: 02Mar2021, when the patient was 65-year-old, for COVID-19 immunization, reaction(s): "some slight dizziness", "fluttering in my chest".  The following information was reported: SYNCOPE (hospitalization, medically significant) with onset 14Dec2022 at 07:30, outcome "unknown", described as "2 days after receiving the last booster I suffered a series of fainting spells"; ATRIOVENTRICULAR BLOCK FIRST DEGREE (hospitalization) with onset Dec2022, outcome "unknown", described as "first degree AV block"; ACOUSTIC STIMULATION TESTS ABNORMAL (hospitalization) with onset Dec2022, outcome "unknown", described as "slightly enlarged heard". The patient was hospitalized for syncope, acoustic stimulation tests abnormal, atrioventricular block first degree (hospitalization duration: 2 day(s). The events "2 days after receiving the last booster i suffered a series of fainting spells", "slightly enlarged heard" and "first degree av block" required physician office visit and emergency room visit. The patient underwent the following laboratory tests and procedures: Electrocardiogram: (Dec2022) first degree AV block; Tests: (Dec2022) slightly enlarged heard; SARS-CoV-2 test: (15Dec2022) Negative. Therapeutic measures were not taken as a result of syncope, acoustic stimulation tests abnormal, atrioventricular block first degree.  Clinical Course: Relevant past drug history: No Drug as Reported and Reaction: Allergy. Vaccine administration date 12Dec2022 03:00 PM (dose number 5, lot number- GL0446, Left arm). The most recent COVID-19 vaccine was administered in Doctor's office/urgent care. The patient did not receive any other vaccines within 4 weeks prior to the COVID vaccine. No other medications the patient received within 2 weeks of vaccination. Patient reported that 2 days after receiving the last booster she suffered a series of fainting spells. She was hospitalized and underwent a battery of tests. The only thing found was a slightly enlarged heard. EKG showed a first-degree AV block, but nothing that they could definitely pinpoint as a cause of her syncope. She was currently on a heart monitor. She was 67 years old, very active, and take no medications. There were no indications prior to these fainting spells that there might be a problem with my heart. She had experienced a fluttering in her chest and some slight dizziness over the past year or so, which she had attributed to hunger, dehydration etc. She had mentioned this to her doctor at her yearly physical in Oct. She was to monitor and make a return visit should they become more prevalent. Adverse event start date: 14Dec2022, start time: 07:30. AE resulted in: Doctor or other healthcare professional office/clinic visit, Emergency room/department or urgent care, Hospitalization, number days hospitalisation: 2, No treatment AE: No Prior to vaccination, the patient was not diagnosed with COVID-19. Since the vaccination, has the patient had been tested for COVID-19. Device Date: 22Dec2022.  No follow-up attempts are needed. No further information expected.