Difficulty breathing; Chest pain; Pericarditis; MI; Blood clot; Body ache; Fever; Headache; Flu symptoms; This is a spontaneous report received from a contactable reporter(s) (Consumer or other non HCP).  A 54-year-old female patient received BNT162b2 (COMIRNATY), on 14Dec2021 as dose 3 (booster), single (Batch/Lot number: unknown) at the age of 54 years for covid-19 immunisation. The patient's relevant medical history included: "Menopause" (unspecified if ongoing), notes: Recently had injection of testosterone and estrogen in pellet form for treatment of menopause. Concomitant medication(s) included: THYROID; TESTOSTERONE taken for menopause; ESTROGEN taken for menopause. Vaccination history included: Covid-19 vaccine (DOSE 1; MANUFACTURER UNKNOWN), for Covid-19 immunization; Covid-19 vaccine (DOSE 2; MANUFACTURER UNKNOWN), for Covid-19 immunization. The following information was reported: PYREXIA (non-serious) with onset 25Apr2022, outcome "recovered" (28Apr2022), described as "Fever"; INFLUENZA (non-serious) with onset 25Apr2022, outcome "unknown", described as "Flu symptoms"; HEADACHE (non-serious) with onset 25Apr2022, outcome "recovered" (29Apr2022); THROMBOSIS (hospitalization, medically significant) with onset 01May2022, outcome "unknown", described as "Blood clot"; MYOCARDIAL INFARCTION (hospitalization, medically significant) with onset 01May2022, outcome "unknown", described as "MI"; PERICARDITIS (hospitalization) with onset 01May2022, outcome "unknown"; CHEST PAIN (hospitalization) with onset 01May2022 at 04:00, outcome "unknown"; DYSPNOEA (hospitalization) with onset 01May2022 at 04:00, outcome "unknown", described as "Difficulty breathing"; PAIN (non-serious), outcome "recovered" (29Apr2022), described as "Body ache". The events "difficulty breathing", "pericarditis" and "chest pain" required emergency room visit. On Sunday 01May she awoke around 4 am with sharp chest pain to wake her from sleep along with difficult breathing on deep breaths. We went to the ER at 5:40 am and after tests to rule out MI or Blood Clot was diagnosed with Pericarditis. Optional Information: Medications: NP Thyroid 60mg, daily vitamin, recently had injection of testosterone and estrogen in pellet form for treatment of menopause. Event took place after use of product. Query: Thank you for reporting the below information to safety 01May2022. Since the information was reported outside of the 24-hour compliance period for AE reporting we are actioned to follow-up on delayed AE reports. Kindly provide a delay reason and confirm completion of AE reporting training. Please also confirm that you understand your reporting responsibilities and the compliance timelines. Agency will send a compliance reminder email later this week. Once received there is no further action required by you. We file this if the documentation is required during an audit. Response: I decided to report this AE that occurred with my wife after reading more into possible reasons for her having developed Pericarditis and then found information online about this side effect possible post clinical trial with the Pfizer mRNA vaccine, and even though she has the vaccine on 14Dec2021, and this event just happened I thought it worth reporting. The patient underwent the following laboratory tests and procedures: Body temperature: (25Apr2022) 101, notes: fever of 101; SARS-CoV-2 test: (25Apr2022) Negative, notes: Covid home test was negative on Monday the 25th; (27Apr2022) Negative, notes: She also took a second Covid home test on Wednesday 27Apr with was negative.  The information on the batch/lot number for BNT162b2 has been requested and will be submitted if and when received.