heart wasn't working very well; Segmental myocarditis/myocarditis after receiving her booster dose using the new formulation of the Pfizer covid19 vaccine.; ejection fraction decreased; fever; This is a spontaneous report received from contactable reporter(s) (Physician) from medical information team. The reporter is the patient.  A 78-year-old female patient received bnt162b2 omi xbb.1.5 (COMIRNATY (2023-2024 FORMULA)), on 17Oct2023 as dose 1, single (Lot number: HO9876) at the age of 78 years, in left deltoid for covid-19 immunisation. The patient's relevant medical history included: "Asthma" (ongoing), notes: Asthma From: Since caller was 1.5 years old; "Labile hypertension" (ongoing), notes: From: Maybe about 18 years ago roughly; "hypertrophic obstructive cardiomyopathy", start date: 2017 (unspecified if ongoing), notes: suspects will last 4 years.; "chronic lung disease" (ongoing). Concomitant medication(s) included: FLU VACCINE VII taken for influenza immunisation as dose number unknown, single. Vaccination history included: bnt162b2 (DOSE 1, SINGLE, Time: Probably around lunch time, Anatomical Site of injection: thinks left deltoid, Route of Administration: intramuscular, Batch/Lot number: EL9264, Expiry: May2021), administration date: 30Jan2021, for COVID-19 immunization; bnt162b2 (DOSE 2, SINGLE, Time: Probably around lunch time, Anatomical Site of injection: Thinks left deltoid, Route of Administration: intramuscular, Batch/Lot number: EM9810 , Expiry: Jun2021), administration date: 20Feb2021, for COVID-19 immunization; bnt162b2 (DOSE 3 (BOOSTER), SINGLE, Time: Probably around lunch time, Anatomical Site of injection: Thinks left deltoid, Route of Administration: intramuscular, Batch/Lot number: FF2590), administration date: 13Oct2021, for Covid-19 immunization; bnt162b2 (DOSE 4 (BOOSTER), SINGLE, Time: Probably around lunch time, Anatomical Site of injection: Thinks left deltoid, Route of Administration: intramuscular, Batch/Lot number: 330368D, Expiry: 30Jun2022), administration date: 18Apr2022, for Covid-19 immunization; bnt162b2;bnt162b2 omi ba.4-5 (DOSE 5 (BOOSTER), SINGLE, Time: Probably around lunch time, Anatomical Site of injection: Thinks left deltoid, Route of Administration: intramuscular, Batch/Lot number: GJ6794), administration date: 19Oct2022, for COVID-19 immunization; moderna bivalent covid-19 vaccine (DOSE 6 (BOOSTER), SINGLE, Time: Probably around lunch time, Anatomical Site of injection: Thinks left deltoid, Route of Administration: intramuscular, Batch/Lot number: 024H22A), administration date: 03Jun2023, for COVID-19 immunisation. The following information was reported: CARDIAC DISORDER (hospitalization) with onset Oct2023, outcome "unknown", described as "heart wasn't working very well"; PYREXIA (non-serious) with onset 21Oct2023, outcome "unknown", described as "fever"; MYOCARDITIS (medically significant) with onset 23Oct2023, outcome "unknown", described as "Segmental myocarditis/myocarditis after receiving her booster dose using the new formulation of the Pfizer covid19 vaccine."; EJECTION FRACTION DECREASED (medically significant) with onset 23Oct2023, outcome "unknown". The patient was hospitalized for cardiac disorder (start date: 23Oct2023, discharge date: 29Oct2023, hospitalization duration: 7 day(s)). The events "heart wasn't working very well", "segmental myocarditis/myocarditis after receiving her booster dose using the new formulation of the pfizer covid19 vaccine." and "ejection fraction decreased" required physician office visit. The patient underwent the following laboratory tests and procedures: Antibody test: (unspecified date) Unknown results; Blood culture: (unspecified date) myocarditis; Body temperature: (21Oct2023) highest was 102 degrees; Chest X-ray: (unspecified date) Unknown results; Echocardiogram: (unspecified date) heart was not functioning right; Ejection fraction: (23Oct2023) down to 30%; Electrocardiogram: (23Oct2023) turned out has segmental myocarditis; SARS-CoV-2 test: (unspecified date) Unknown results; Viral test: (unspecified date) unknown results; (unspecified date) myocarditis. Therapeutic measures were taken as a result of cardiac disorder, myocarditis. Clinical course: Patient mentioned that she had myocarditis after receiving her booster dose using the new formulation of the Pfizer covid19 vaccine. She explained that this was her 7th dose of covid vaccine. She wanted to know if there are other reports of myocarditis in her age group with the new formulation of the covid19 vaccine. Dates when patient was in hospital for heart wasn't working very well: 23Oct2023 to 29Oct2023. On 21Oct2023 in the evening, patient developed a fever, highest was 102 degrees Fahrenheit. She did not have any other symptoms, no sore throat or runny nose or cough or chest pain or other aches and pains, confirmed did not have any other symptoms. She contacted her pulmonologist because she had a chronic lung disease and pulmonologist wanted her to go to hospital to get a chest x-ray and the Covid PCR. So she went to hospital on Monday, 23Oct2023, and did EKG, was very alarmed about EKG, thought she had a heart attack, did emergency cardiac catherization, turned out had segmental myocarditis, a portion of heart was affected, not entire heart. Later during call clarified and confirmed she was admitted into the hospital. Hospital did blood cultures, did viral studies, and final conclusion was most likely that myocarditis was a consequence of the vaccine. Hypertrophic obstructive cardiomyopathy, which she was diagnosed with sometime since 2017, and she suspected would last 4 years. Admitted into the hospital 23Oct2023. Clarified the reason for admission was that realized that her heart wasn't working very well, did emergency echocardiogram, and part of wall of heart was not functioning right, ejection was down to 30%. She was short of breath and was oxygen dependent. Had gotten a flu vaccine but was more than 2 weeks prior, recommended to separate the vaccines by 10 days but because of travel she couldn't do the 10 day separation. Patient unknown at time of call what the specific name of the flu vaccine was and what date the flu vaccine was administered. Clarified the chronic lung disease that caller mentioned earlier, is from the asthma. Did a viral panel and also did antibody test, was not the nasal swab. Had no family medical history relevant to Adverse Events.; Sender's Comments: Based on temporal association and known safety profile a contributory  role of bnt162b2 omi xbb.1.5 to the reported events cannot  be totally  excluded.  The patient's history of hypertrophic obstructive cardiomyopathy is a risk factor for the cardiac events.  Case will be reassessed if additional information is received.  The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to Regulatory Authorities, Ethics Committees and Investigators, as appropriate.