Caller experienced arrhythmia 2 days after she got the dose of the Pfizer BioNTech Covid-19 Vaccine; This is a spontaneous report from a contactable consumer (patient). A 73-year-old female patient received BNT162B2 (PFIZER-BIONTECH COVID-19 mRNA VACCINE, lot number: unknown, expiry date: unknown), via unspecified route of administration on 26Mar2021 as dose 2, single for COVID-19 immunisation. Patient medical history and concomitant medications were not reported. Patient previously took first dose of BNT162B2 (lot number: unknown, expiry date: unknown) via unspecified route of administration on 25Feb2021 (at the age of 73-year-old) as dose 1, single for COVID-19 immunisation. Patient wanted to know if they could provide some treatment recommendations specific to the AE that she was experiencing. Patient experienced arrhythmia 2 days after she got the dose of the Pfizer BioNTech Covid-19 Vaccine. She was also prescribed Eliquis by her doctor that could provide clinical trial result findings if this was a reported AE however they could not provider treatment recommendations to individual patients. She was referred to healthcare professional (HCP). She expressed frustration as to why she could not speak with a medical doctor from Pfizer and got medical recommendations for the adverse event (AE) that she was experiencing. She also stated that she could not talk to them properly because of the delay. The patient received the COVID vaccine on 26th, but did not specific which dose it was. On 27th, the patient experienced an arrhythmia, and as a result her doctor now wants her on a blood thinner, specifically Eliquis. Her doctor also wants a loop monitor. She was afraid to be on medicines for long periods of time. She was frightened this may go into something long-term and it might effect her for the rest of her life negatively. The doctor didn't seem to have answers, more so suggestions on what to do and some of those suggestions could be bad for because she is in her 70's and she did not have that much longer to live per se. She did not want to be taking this medicine (Eliquis) and would like to get a second opinion with Pfizer's Medical Information team to determine if this is alright and what could be done about this. She could not imagine being on medicine for the rest of her life and that's what they say about Eliquis. She already did not like Eliquis per se. She wanted to hear what Pfizer was telling people to do. She inquired had any other people experienced this and what were the recommendations and if there another doctor should go and see to get a second opinion. She wanted to talk with Pfizer Medical Information first and see what they say to her and she would go from there. The outcome of event was unknown.   No further details were provided or obtained. Information on Lot/Batch information has been requested.  Follow-up attempts completed. No further information is expected.; Sender's Comments: 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.