Changes in kidney function tests; Joint pain; Back pain; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP and Pharmacist). The reporter is the patient. Other Case identifier(s): 2021-US-023959 (RA).  A 68 year-old female patient (not pregnant) received bnt162b2 (BNT162B2), administration date Apr2021 (Batch/Lot number: unknown) as dose 2, single for covid-19 immunisation; anastrozole (ARIMIDEX), oral since 2012 (ongoing) (Lot number: 505406, Expiration Date: Jun2022) at 1 mg daily for breast cancer. Relevant medical history included: "breast cancer" (ongoing); "osteoporosis" (ongoing), notes: unspecified injection every 6 months for osteoporosis; "high cholesterol" (ongoing); "Allergies: unspecified oral cholesterol medications (tingly legs)" (unspecified if ongoing). The patient took concomitant medications. Vaccination history included: Bnt162b2 (DOSE: 1), for COVID-19 immunization. The following information was reported: BACK PAIN (non-serious) with onset Apr2021, outcome "not recovered", described as "Back pain"; RENAL FUNCTION TEST ABNORMAL (non-serious) with onset Aug2021, outcome "unknown", described as "Changes in kidney function tests"; ARTHRALGIA (non-serious) with onset Apr2021, outcome "not recovered", described as "Joint pain". The events "back pain", "changes in kidney function tests" and "joint pain" were evaluated at the physician office visit. Relevant laboratory tests and procedures are available in the appropriate section. The action taken for anastrozole was dosage not changed. The consumer stated that she will be having her bone density, sonogram, and mammogram sometime around 13Jan2022, but she did not know when her follow-up appointment will be to obtain the results. She has not had any further kidney function tests. The consumer was still having back and joint pain.  Additional information: The patient stated that a cardiologist tested her heart with an unspecified "x-ray" to check for a blood clot, but the results came back within normal limits. In approximately Apr2021, patient starting noticing back pain and generalized joint pain. She feels it started shortly after receiving her 2nd dose of Pfizer Covid19 vaccine. Symptoms have continued and she feels the vaccine may be the cause but not sure. Patient notes she is also following with a cardiologist who had tested her heart with "x-ray" to check for blood clot but evrything came back normal. She continues to follow with him for high cholesterol and when he hecked labs on an unspecified date in Aug2021, she was noted to have changes in her kidney unction tests which she states were done via blood and urine. She does not know the exact values nly that they were out of range. She will be having them checked again the end of Nov2021 long with a bone density test. Patient states that her doctor didn't think the Arimidex was the cause of her symptoms but she has been concerned and researching on her own looking for possible cause and therefore reported her symptoms to (Name). Patient had to get to work and was going through the tunnel so was unable to provide any additional details. She states her bone density, sonogram, mammogram in mid Jan2022, she thinks it will be around 13Jan2022, and then she does not know when her follow up appointment will be to obtain the results. Her doctor did not think Arimidex was the cause of her symptoms. She has not had any further kidney function tests either. She is still having the back and joint pain. She thinks she won't really know anything, until probably the end of Jan2022. Medications and supplements: Vitamins, unspecified injection every 2 weeks for high cholesterol, unspecified injection every 6 months for osteoporosis.   No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.