Interchange of vaccine products; Shortness of breath; Myocarditis/feeling was worse than what she normally has.; Myocarditis/feeling was worse than what she normally has.; chest pain; sleepiness; bunch of PVCs in a row; This is a spontaneous report received from contactable reporter(s) (Nurse) from medical information team. The reporter is the patient.  A 78-year-old female patient received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), on 15Dec2022 as dose 5 (booster), single (Lot number: GH9697) at the age of 78 years intramuscular, in left arm for covid-19 immunisation. The patient's relevant medical history was not reported. There were no concomitant medications. Vaccination history included: moderna coviD-19 vaccine (dose 1, Lot Number: 206L20A), administration date: 15Jan2021, when the patient was 76-year-old, for COVID-19 immunization; moderna coviD-19 vaccine (dose 2, Lot Number: 015M20A. Myocarditis  on apr2021), administration date: 12Feb2021, when the patient was 76-year-old, for COVID-19 immunization, reaction(s): "Myocarditis", "Shortness of breath"; moderna coviD-19 vaccine (dose 3, Lot Number: 034F21A), administration date: 11Nov2021, when the patient was 77-year-old, for COVID-19 immunization; BNT162b2 (dose 4 (booster); Lot Number: FJ4991), administration date: 23Jun2022, when the patient was 77-year-old, for COVID-19 immunization; Flu shot, for Immunization. The following information was reported: MYOCARDITIS (medically significant, life threatening), CONDITION AGGRAVATED (life threatening) all with onset 18Dec2022, outcome "unknown" and all described as "Myocarditis/feeling was worse than what she normally has."; VENTRICULAR EXTRASYSTOLES (non-serious) with onset 18Dec2022, outcome "unknown", described as "bunch of PVCs in a row"; CHEST PAIN (life threatening) with onset 18Dec2022, outcome "recovered" (2022); SOMNOLENCE (life threatening) with onset 18Dec2022, outcome "recovered" (2022), described as "sleepiness"; INTERCHANGE OF VACCINE PRODUCTS (medically significant, life threatening), outcome "unknown"; DYSPNOEA (non-serious), outcome "unknown", described as "Shortness of breath". The patient underwent the following laboratory tests and procedures: Echocardiogram: Unknown Results, notes: they will do an echo then.  Clinical information: She stated she "had myocarditis from a previous Covid vaccine" 1st three vaccines she received were Moderna and the last 2 were Pfizer booster doses, last was on 15Dec2022. She stated that she didn't feel well for a bit but went on home. She was sitting down and reading the information that they had given her and realized that she had myocarditis in April, which would have been after her Mar dose of a Covid booster. She stated that she doesn't have exact dates for this Myocarditis. She stated that it was approximately in the middle of Apr2021. She stated that she had terrible shortness of breath when she had Myocarditis in Apr2021. When prompted for specific seriousness criteria related to these events the caller replies with yes after the call handler asks life-threatening, then stated no she was not hospitalized. Stated that she didn't put it together, the myocarditis and the vaccine, until after she read the paper. She denies any other medications, medical conditions, labs, testing, or treatments relevant to these events. She stated that she will go for a checkup related to her myocarditis in Mar and they will do an echo then. She got this most recent booster on the 15th. She stated sometimes she still feels the myocarditis, she will get a pain in her heart and gets sleepy. She stated that after this most recent booster, on about 18Dec2022, this feeling was worse than what she normally has. She stated that it felt like she had a bunch of PVCs in a row, she got sleepy like she was when she had myocarditis. She stated that when she left the room after the vaccine, she started to feel funny. They told her to wait 10-15 minutes. She stated she got myocarditis form the Moderna vaccines and had chest pain, sleepiness and shortness of breath with the most current Pfizer booster dose. She got the shot on 15Dec2022 and has never had any side effects from previous Flu shots or her 5 previous Covid shots. She stated that chest pain, sleepiness began for her on 18Dec2022. She doesn't know how long it lasted, a few days. She stated that she cannot say that it was completely gone, but it wasn't like it was the first time. She stated that the symptoms from the myocarditis in Apr2021 have never gone away completely for her. She stated that her symptoms that began on 18Dec2022 probably lasted about a week. She was so sleepy for at least 2 weeks she could not do much. Serious: No.; Sender's Comments: Based on limited information in the case, a possible causal association between all the reported events and the suspect drug cannot be excluded.  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 RAs, Ethics Committees, and Investigators, as appropriate.