tachycardia; heart rate of 140bpm (typically hover around 75); I had a fever of 101; chest pains; palpitations; fatigue; D-dimer was somewhat elevated; I felt much worse; faint; A few hours after vaccination I had chills but no fever.; This is a spontaneous report from a contactable other HCP (patient).   A 28-year-old female patient received bnt162b2 (BNT162B2), dose 3 via an unspecified route of administration, administered in arm left on 01Oct2021 16:30 (at the age of 28-year-old) (Batch/Lot Number: FE3590) as dose 3 (booster), single for COVID-19 immunisation, administered at Pharmacy or Drug Store.  Medical history was none. No known allergies. Concomitant medication(s) included omeprazole (OMPRAZOLE) 14 day series; ethinylestradiol, levonorgestrel (MARLISSA hormonal BC), both taken for an unspecified indication, start and stop date were not reported. The patient received bnt162b2 (BNT162B2), dose 1 via an unspecified route of administration, administered in arm left on 06Jan2021 (at the age of 28-year-old) (Batch/Lot Number: EL3246) as single dose, dose 2 via an unspecified route of administration, administered in arm left on 28Jan2021 (at the age of 28-year-old) (Batch/Lot Number: EN5318) as single dose for COVID-19 immunisation and experienced no side effects. Patient was not pregnant. No other vaccine in four weeks. Patient has not experienced COVID prior vaccination. COVID was not tested post vaccination. The patient experienced heart rate of 140bpm (typically hover around 75) (medically significant) on 02Oct2021 13:00 with outcome of recovering, tachycardia (medically significant) on 02Oct2021 21:00 with outcome of recovering, faint (medically significant) on 02Oct2021 with outcome of recovering, a few hours after vaccination she had chills but no fever (non-serious) on 01Oct2021 21:00 with outcome of recovering, fatigue (non-serious) on 01Oct2021 21:00 with outcome of recovering, she felt much worse (condition aggravated) (non-serious) on 02Oct2021 with outcome of recovering, she had a fever of 101 (non-serious) on 02Oct2021  13:00 with outcome of recovering, chest pains (non-serious) on 02Oct2021 with outcome of recovering, palpitations (non-serious) on 01Oct2021 21:00 with outcome of recovering, d-dimer was somewhat elevated (non-serious) on 02Oct2021 with outcome of recovering.  Events resulted in Emergency room/department or urgent care. The clinical course of events was as follows: A few hours after vaccination on 01Oct2021 she had chills but no fever. The next day, on 02Oct2021 she felt much worse. Around 1pm she had a fever of 101 and a heart rate of 140bpm (typically hover around 75). She started getting chest pains, palpitations, and feeling feverish/faint. She did not have shortness of breath but decided to go to the ER just in case she had myocarditis/pericarditis. They did two EKGs while she was there and showed tachycardia and a few "benign palpitations" but no arrhythmias indicative of myocarditis/pericarditis according to her docs. Troponin was normal. D-dimer was somewhat elevated, so they did a CT scan. Scan didn't show anything in her lungs/heart. They put her on IV fluids which helped lower her heart rate and ultimately sent me home with a heart rate around 85-90 & a temperature of 100 to take Tylenol and fluids. After a night of sleep on 03Oct2021 her heart rate and temperature are normal, but still have lingering right-sided chest pain/fatigue.   No follow-up attempts are needed. No further information is expected.; Sender's Comments: Based on a temporal association, a causal relationship between the reported events and BNT162B2 booster dose is considered possible.  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.