However he recently has had a re-emergence of symptoms AFTER getting the Pfizer vaccine regimen/then the vaccine, now resurgence of heart rhythm irregularity; irregular pattern; worsening, more frequent episodes late Sept; mild rapid beat episodes early Sept; mild occasional arrythmia early Aug; administration date: 28Jul2021, dose number: 2/prev dose administration date: 15Jun2021, prev dose dose number: 1; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the parent.  A 12 year-old male patient received bnt162b2 (BNT162B2), administered in arm left, administration date 28Jul2021 12:00 (Lot number: FA6780) at the age of 12 years as dose 2, single for covid-19 immunisation. Relevant medical history included: "AV node ablation procedure", start date: 2018, stop date: 2018, notes: After surgery, his arrhythmia and rapid beat episodes virtually disappeared for years. There were no concomitant medications. Known allergies: none. Other vaccine in four weeks: No. Other medications in two weeks: None. Covid prior vaccination: No.Vaccination history included: Bnt162b2 (Lot number = EW0187, at 12:00 PM, Left arm.), administration date: 15Jun2021, when the patient was 12 years old, for Covid-19 immunization, at Pharmacy or Drug Store.  The following information was reported: ARRHYTHMIA (medically significant) with onset 06Aug2021 12:00, outcome "recovered with sequelae", described as "mild occasional arrythmia early Aug"; DISEASE RECURRENCE (medically significant), outcome "recovered with sequelae", described as "However he recently has had a re-emergence of symptoms AFTER getting the Pfizer vaccine regimen/then the vaccine, now resurgence of heart rhythm irregularity"; CONDITION AGGRAVATED (medically significant) with onset Sep2021, outcome "recovered with sequelae", described as "worsening, more frequent episodes late Sept"; HEART RATE INCREASED (medically significant) with onset Sep2021, outcome "recovered with sequelae", described as "mild rapid beat episodes early Sept"; HEART RATE IRREGULAR (medically significant) with onset 01Oct2021, outcome "recovered with sequelae", described as "irregular pattern"; INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (non-serious) with onset 28Jul2021, outcome "unknown", described as "administration date: 28Jul2021, dose number: 2/prev dose administration date: 15Jun2021, prev dose dose number: 1".   The events "mild occasional arrythmia early aug", "mild rapid beat episodes early sept", "worsening, more frequent episodes late sept", "irregular pattern" and "however he recently has had a re-emergence of symptoms after getting the pfizer vaccine regimen/then the vaccine, now resurgence of heart rhythm irregularity" were evaluated at the physician office visit and emergency room visit in 1st week of Oct and prescribed metoprolol. 12Oct Telemed visit w/(hospital), modified med protocol to-date, reduced rapid beat episodes but occasional arrhythmia and more rare rapid beat episodes (1-2 min) while on meds. If accidental missed dose, almost guaranteed episode follows. Again, he was free and clear for years, then the vaccine, now resurgence of heart rhythm irregularity. The patient underwent the following laboratory tests and procedures: electrocardiogram: (01Oct2021) irregular pattern; heart rate: (Sep2021) rapid; sars-cov-2 test: (24Dec2021) negative. Therapeutic measures were taken as a result of arrhythmia, heart rate increased, condition aggravated, heart rate irregular, disease recurrence. Treatment with Metoprolol tartrate prescribed.  No follow-up attempts are possible, No further information is expected.