She is not well; Bilateral leg pain/severe leg pain./pain went to the right arm/pain went to her left arm; calf and thigh muscles (pain); also the joints (pain); having trouble walking; couldn't sleep; couldn't stand the sheet on her leg; for Vitamin D3, which was low; This is a spontaneous report received from a contactable reporter(s) (Nurse) from medical information team. The reporter is the patient.  A 78-year-old female patient received BNT162b2 (BNT162B2), in 2021 as dose 3 (booster), single (Lot number: FF2590, Expiration Date: 31Dec2021), in left arm for covid-19 immunisation. The patient's relevant medical history was not reported. The patient took concomitant medications.She doesn't take any other medications other than vitamins. She took magnesium thinking it would help; took 500mg tablets of Magnesium. Magnesium didn't help the pain. Was already a daily multi-vitamin. Clarified all of her vitamins are over the counter. She does not have any prescription medications. Vaccination history included: BNT162b2 (Dose 1, Time: morning, 10AM, LOT: PFR EN6204, Anatomical Site of injection: Left upper arm), administration date: 08Mar2021, when the patient was 76-year-old, for COVID-19 immunization; BNT162b2 (Dose 2, Time: 7:59AM, LOT: PFR EP6955, Anatomical Site of injection: left upper arm), administration date: 29Mar2021, when the patient was 76-year-old, for COVID-19 immunization. The following information was reported: PAIN IN EXTREMITY (disability) with onset 2021, outcome "unknown", described as "Bilateral leg pain/severe leg pain./pain went to the right arm/pain went to her left arm"; MALAISE (disability) with onset 2021, outcome "unknown", described as "She is not well"; ARTHRALGIA (disability) with onset 2021, outcome "unknown", described as "also the joints (pain)"; MYALGIA (disability) with onset 2021, outcome "unknown", described as "calf and thigh muscles (pain)"; INSOMNIA (disability) with onset 2021, outcome "unknown", described as "couldn't sleep"; DYSSTASIA (disability) with onset 2021, outcome "unknown", described as "couldn't stand the sheet on her leg"; VITAMIN D DECREASED (disability) with onset 2021, outcome "unknown", described as "for Vitamin D3, which was low"; GAIT DISTURBANCE (disability) with onset 2021, outcome "unknown", described as "having trouble walking". The events "she is not well", "bilateral leg pain/severe leg pain./pain went to the right arm/pain went to her left arm", "calf and thigh muscles (pain)", "also the joints (pain)", "having trouble walking", "couldn't sleep", "couldn't stand the sheet on her leg" and "for vitamin d3, which was low" required physician office visit. Patient is not well and is very concerned about it. She didn't have a doctor for 10 years until she went a couple months ago because of the severe leg pain. She couldn't sleep, couldn't stand the sheet on her leg. She has been on feet her whole life. Was a hospital and surgical nurse. Then she did read a blurp about side effects and never thought about that. The more she thought, she did go to a primary care doctor. Her lab work was good except for Vitamin D3, which was low, not excruciatingly low. She now takes 5,000mg of vitamin D3 a day. Her doctor was going to write a prescription but she already takes vitamin D3 so she advised her doctor she'll just take more of it. Attempted to clarify dose of 5,000mg but caller would not reclarify. She has a follow up appointment on 01Jun2023, but she doesn't feel any better. Is having trouble walking. The pain went to her left arm, the middle of arm for 3-4 days. Then the left arm got better, but the pain went to the right arm. Her legs are still terrible. She doesn't know and all she is doing is asking questions because when she goes to see her primary care doctor. She is not a big doctor fan. If she's no better by 01Jun2023, primary doctor is going to send her to an orthopedic doctor for knee replacements. Caller states she doesn't need knee replacements. Seriousness criteria: Disabling at times. Always manages to get up in the night, just to get to the bathroom, but the paint is terrible then. It's excruciating, it's awful. During the day, she can tolerate it and not be in such terrible pain. The patient underwent the following laboratory tests and procedures: Blood test: good, notes: Her lab work was good; Vitamin D: low, not excruciatingly low, notes: Her lab work was good except for Vitamin D3, which was low, not excruciatingly low. Therapeutic measures were taken as a result of malaise, pain in extremity, myalgia, arthralgia, gait disturbance, insomnia, dysstasia, vitamin d decreased.; Sender's Comments: As there is limited information in the case provided, the causal association between the reported events and the suspect drug BNT162B2 cannot be excluded. The case will be reassessed once new information is available.   The impact of this report on the benefit/risk profile of the Pfizer drug 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. ,Linked Report(s) : US-PFIZER INC-202300192113 Same reporter/patient/drug, different AE.;