myocarditis; pericarditis; fatigue/unusual tiredness; chest pain; fever; off label use; interchange of vaccine products; mycotoxicosis; this is a spontaneous report received from a contactable reporter(s) (consumer or other non hcp) from the regulatory agency. the reporter is the patient. regulatory number: gb-mhra-webcovid-202202171515581090-lh7gd. other case identifier(s): gb-mhra-adr 26613431. a 58 year-old male patient received bnt162b2 (comirnaty), administration date 26nov2021 (batch/lot number: unknown) at the age of 58 years as dose 3 (booster), single for covid-19 immunisation. relevant medical history included: "knee problems" (unspecified if ongoing). patient has not had symptoms associated with covid-19. patient is not enrolled in clinical trial. the patient's concomitant medications were not reported. vaccination history included: covid-19 vaccine astrazeneca (dose 1), administration date: 11mar2021, for covid-19 immunisation; covid-19 vaccine astrazeneca (dose 2), administration date: 17may2021, for covid-19 immunisation. the following information was reported: off label use (medically significant) with onset 26nov2021, outcome "unknown", described as "off label use"; interchange of vaccine products (medically significant) with onset 26nov2021, outcome "unknown", described as "interchange of vaccine products"; mycotoxicosis (medically significant) with onset 26nov2021, outcome "not recovered", described as "mycotoxicosis"; myocarditis (medically significant), outcome "unknown", described as "myocarditis"; pericarditis (medically significant), outcome "unknown", described as "pericarditis"; fatigue (non-serious), outcome "unknown", described as "fatigue/unusual tiredness"; chest pain (non-serious), outcome "unknown", described as "chest pain"; pyrexia (non-serious), outcome "unknown", described as "fever". clinical course of the events: patient thought that he was taking a heart attack and was taken to hospital by ambulance and got blood test in hospital. the symptoms did not lead to hospital stay, and no diagnosis was made by a medical professional. hospital said they didn't know what was wrong with his heart but it was not a hear attack. no treatment was given due to the symptoms. the report does relate to possible inflammation of the heart (myocarditis or pericarditis). there were no imaging done (chest x-ray, echocardiogram, cardiac mri, chest computerised tomography (ct)). the patient underwent the following laboratory tests and procedures: blood test: unknown result; sars-cov-2 test: negative, notes: no - negative covid-19 test. patient has not tested positive for covid-19 since having the vaccine. no follow-up attempts are possible; information about lot/batch number cannot be obtained. no further information is expected