t-wave inversion; The rash was like tiny red dots that kids get when they were little.; Cardio Myositis; 3rd booster shot with Pfizer COVID 19 vaccine; Slight rash on truncal and thoracic area; Fever of 103 degrees Fahrenheit; His Troponin levels were increased; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the parent.  A 17 year-old male patient received bnt162b2 (BNT162B2), administration date 28Dec2021 (Lot number: FD0809, Expiration Date: 31Jan2022) at the age of 17 years as dose 3 (booster), single for covid-19 immunisation. Relevant medical history included: "He is heavy but not obese" (unspecified if ongoing). There was no family medical history relevant to AE(s). There were no concomitant medications. Prior vaccinations (within 4 weeks), the patient did not receive other vaccinations within four weeks prior to the first administration date of the suspect vaccine(s). The patient did not have any adverse event following prior vaccinations. Vaccination history included: Bnt162b2 (Dose: 01, Lot Number: EN6204 expiration is unknown and it could say EW6204, Anatomical location; left deltoid), administration date: 09Apr2021, when the patient was 16 years old, for COVID-19 immunization, reaction(s): "No adverse event"; Bnt162b2 (Dose: 02, Lot Number: EW OR EN0161, Anatomical location; left deltoid), administration date: 30Apr2021, when the patient was 16 years old, for COVID-19 immunization, reaction(s): "No adverse event". The following information was reported: IMMUNISATION (medically significant) with onset 28Dec2021, outcome "unknown", described as "3rd booster shot with Pfizer COVID 19 vaccine"; MYOCARDITIS (medically significant) with onset 03Jan2022, outcome "recovering", described as "Cardio Myositis"; ELECTROCARDIOGRAM T WAVE INVERSION (medically significant), outcome "unknown", described as "t-wave inversion"; RASH (medically significant) with onset 28Dec2021, outcome "recovering", described as "Slight rash on truncal and thoracic area"; PYREXIA (medically significant) with onset 28Dec2021, outcome "recovering", described as "Fever of 103 degrees Fahrenheit"; TROPONIN INCREASED (non-serious) with onset 2021, outcome "unknown", described as "His Troponin levels were increased"; ERYTHEMA (non-serious), outcome "unknown", described as "The rash was like tiny red dots that kids get when they were little.". The events "cardio myositis", "slight rash on truncal and thoracic area", "fever of 103 degrees fahrenheit", "his troponin levels were increased" and "the rash was like tiny red dots that kids get when they were little." were evaluated at the physician office visit. The patient underwent the following laboratory tests and procedures: blood test: (unspecified date) unknown result; body temperature: (28Dec2021) 103 degrees; c-reactive protein: (unspecified date) unknown result; diagnostic aspiration: (unspecified date) unknown result; echocardiogram: (unspecified date) fine; electrocardiogram: (unspecified date) t-wave inversion, notes: which suggests he has some problems still; full blood count: (unspecified date) unknown result; troponin: (unspecified date) increased; x-ray: (unspecified date) unknown result. Therapeutic measures were taken as a result of myocarditis, electrocardiogram t wave inversion, rash, pyrexia, troponin increased, erythema. The patient had slight rash on truncal and thoracic in the evening of 28Dec2021, and throughout the next day. He also had fever of 103 degrees Fahrenheit in the evening of 28Dec2021 post vaccination. That was the only time he got either of those and it was after the third dose as well. The rash was like tiny red dots that kids get when they were little. They just thought he was having a robust immune response. He had a fever of 103 degrees Fahrenheit for 4 days. The rash was on his stomach and back, his truncal and thoracic region. His symptoms started New Years Eve. It was very serious when he had it on 31Dec2021, but she thought he was having reflux. He had cardio myositis first thing on 03Jan2022, Monday morning. His troponin levels were already going down by the time he was seen on Monday. It had improved, but he had a t-wave inversion, which suggests he has some problems still. But he was mean as ever and would probably be fine. The patient did not visit to an emergency room. The patient had several physicians and lab visits. She did not know all of it, CBC, Tropin, Cardiac, C Reactive Protein monitoring. He also received palliative care, Ibuprofen, rest and monitoring. He had been seeing a cardiologist. They had been caught up being sick, so today was the first day they have not had an appointment or anything.  The reporter's assessment of causality for the events Cardio Myositis, Slight rash on truncal and thoracic area, Fever of 103 degrees Fahrenheit was related with the suspect bnt162b2.