third COVID-19 vaccine, a Pfizer-BioNTech, and 6 months after his initial two series Astra-Zeneca COVID-19 vaccines; COVID-19 vaccine-associated myocarditis; This is a literature report for the following literature source(s):  A 32-year-old male patient received BNT162b2, BNT162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), as dose 3 (booster), single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history included: "allergy to penicillin" (unspecified if ongoing); "symptomatic COVID-19 infection" (unspecified if ongoing), notes: 1.5 years ago, without cardiac involvement; "never smoked tobacco" (unspecified if ongoing). The patient's concomitant medications were not reported. Vaccination history included: Astrazeneca covid-19 vaccine (dose 1), for COVID-19 immunisation; Astrazeneca covid-19 vaccine (dose 2), for COVID-19 immunisation. The following information was reported: INTERCHANGE OF VACCINE PRODUCTS (hospitalization, medically significant), outcome "recovered", described as "third COVID-19 vaccine, a Pfizer-BioNTech, and 6 months after his initial two series Astra-Zeneca COVID-19 vaccines"; MYOCARDITIS (hospitalization, medically significant), 3 days after the suspect product(s) administration, outcome "recovered", described as "COVID-19 vaccine-associated myocarditis". The event "covid-19 vaccine-associated myocarditis" required emergency room visit. The patient underwent the following laboratory tests and procedures: Blood pressure measurement: 157/92; Cardiac function test: revealed regular rate, notes: and rhythm, normal S1 and S2, without murmur or rub.No elevation of his jugular venous pressure or lower extremity edema; C-reactive protein: less than 0.5; 4.3, notes: during hospitalization; Echocardiogram: revealed a normal left ventricular size, notes: and function without pericardial effusion; Electrocardiogram: revealed diffuse ST segment elevations, notes: revealed diffuse ST segment elevations; Heart rate: 82; Magnetic resonance imaging heart: revealed mid apical, notes: and lateral wall subepicardial enhancement; Oxygen saturation: 98 %, notes: on room air; Respiratory rate: 16; Troponin: 897, notes: initial; 1215, notes: increased 2 hours later. Therapeutic measures were taken as a result of myocarditis.  Clinical course: A healthy male presented to the emergency department with acute non-exertional chest pressure with radiation to the back and jaw three days after receiving his third COVID-19 vaccine, a Pfizer-BioNTech, and 6 months after his initial two series Astra-Zeneca COVID-19 vaccines. His chest pain was improved with leaning forward. He had associated fatigue, myalgias, and headache. Past medical history was notable for symptomatic COVID-19 infection 1.5 years ago, without cardiac involvement. He had no family history of early cardiac disease, never smoked tobacco, and has an allergy to penicillin. He took no daily medications. He appeared comfortable with a blood pressure of 157/92, heart rate 82, respiratory rate 16, and oxygen saturation on room air of 98 percent. Cardiac exam revealed regular rate and rhythm, normal S1 and S2, without murmur or rub. No elevation of his jugular venous pressure or lower extremity edema. His initial high sensitivity troponin was 897 which increased and peaked at 1,215 two hours later. Electrocardiogram revealed diffuse ST segment elevations. Transthoracic echocardiogram revealed a normal left ventricular size and function without pericardial effusion. Cardiac magnetic resonance imaging revealed mid apical and lateral wall subepicardial enhancement. He was treated with colchicine and Ibuprofen. He discharged after three symptom free days with a plan to continue these therapies for 3 months. Two weeks later, he continued to be symptom free. He reported side effects taking Ibuprofen, but continued on colchicine for the recommended 3 months. At this visit his C-reactive protein was < 0.5 from 4.3 during hospitalization and the patient was instructed to resume his usual activities. Myocarditis is a rare but serious adverse event that can happen after mRNA based COVID-19 vaccination. It is three to five times more frequent following the second dose compared to the first; however patients with prior COVID-19 infection are at higher risk following the first dose. COVID-19 vaccine-associated myocarditis most often occurs in males aged 12-24, and as men increase in age, the reported incidence decreases. This case demonstrates the most common clinical course of COVID-19 vaccineassociated cases of myocarditis. Symptom onset was within seven days of vaccination, most often day 2-3, which contrasts with the more indolent clinical course of viral myocarditis. An overwhelming majority of cases require hospitalization. Symptoms most commonly resolve prior to discharge from the hospital. Diagnostically, most cases have a grossly normal echocardiogram. Cardiac magnetic resonance imaging shows myocardial edema and late gadolinium enhancement, similar to findings in nonvaccine myocarditis. The optimal duration of exercise restriction in adults post-myocarditis is uncertain. The normalization of C-reactive protein at follow up visits could be used as a tool to aid clinicians in deciding timing of resuming activity. While COVID-19 vaccine-associated myocarditis is most often seen in adolescent males, it can also occur in adults. The clinical course is favorable, with rapid onset of symptoms and rapid resolution. Cardiac magnetic resonance imaging is an essential, noninvasive, high sensitivity imaging test used for diagnosis of myocarditis. C-reactive protein can function as an indicator of active disease at follow up.; Sender's Comments: Based on the available information, a possible contributory role of the suspect product cannot be completely excluded for reported events , interchange of vaccine products, and Myocarditis due to a plausible temporal association.The impact of this report on the benefit-risk profile of the Pfizer product and on the conduct of the study 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