Low oxygen level; First dose: 04mar2021; second dose: 25Apr2021; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the patient.  A 61-year-old female patient (not pregnant) received BNT162b2 (BNT162B2), on 25Apr2021 at 15:15 as dose 2, single (Lot number: EW0172) at the age of 60 years intramuscular, in right arm for covid-19 immunisation. The patient's relevant medical history included: "PE/Pulmonary Embolism", start date: Mar2013, stop date: Mar2013, notes: Illness/AE: PE, Pertinent details: Hospitalized for week; Began blood thinners; "Low oxygen levels" (unspecified if ongoing), notes: Low oxygen levels (avg. 87); "Anxiety" (unspecified if ongoing); "Depression" (unspecified if ongoing); "Endometriosis", start date: Jan1987, stop date: Jul1991, notes: Illness/AE: Endometriosis, Pertinent details: Full hysterectomy; "Gallbladder (Gall stones)", start date: Apr2000, stop date: Apr2000, notes: Gallbladder (Gall stones): Had gallbladder removed; "Appendixs blocked", start date: 01May2017, stop date: 01Jul2017, notes: Illness/AE: Appendixs blocked, Pertinent details: Appendectomy. Concomitant medication(s) included: METFORMIN oral taken for diabetes mellitus, start date: 2017 (ongoing); ROSUVASTATIN oral taken for blood cholesterol increased, start date: 2005 (ongoing); NORTRIPTYLINE oral taken for migraine, start date: 2010 (ongoing). Past drug history included: Xarelto, start date: 2017, for PE, notes: Drug (Trade and Generic): Xarelto 20 mg, Route: By mouth. Vaccination history included: BNT162b2 (Dose: 1, Time: 03:00 PM, Anatomical site: Left Upper Arm, Route : Intramuscular, Batch/Lot number: EW0150), administration date: 04Mar2021, when the patient was 60-year-old, for COVID-19 immunization. The following information was reported: INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (non-serious) with onset 25Apr2021 at 15:15, outcome "unknown", described as "First dose: 04mar2021; second dose: 25Apr2021"; OXYGEN SATURATION DECREASED (medically significant) with onset May2021, outcome "not recovered", described as "Low oxygen level". The event "low oxygen level" required physician office visit. The patient underwent the following laboratory tests and procedures: Blood test: Unknown result; Oxygen saturation: avg. 87, notes: Low oxygen levels. Therapeutic measures were taken as a result of oxygen saturation decreased. The patient was on oxygen mask, fulltime.  Clinical course: It was reported that, prior to vaccination, the patient was not diagnosed with COVID-19. Since the vaccination, the patient had not been tested for COVID-19. The patient did not receive other vaccines within 4 weeks prior to the vaccination. Family Medical History Relevant to AE(s): Father- 91 years old (living) Bypass surgery on heart at 72, High Cholesterol, Blood cancer 2019, Mother- 87 passed away heart failure and pneumonia, Had heart attack, 2 strokes Brain aneurysm, High blood pressure, Oldest Sister- Brain aneurysm 2, Diabetic, High Cholesterol, Depression, Middle Sister- Thyroid problems, High Cholesterol, Diabetic, Depression, Blood clot in lungs. The patient had many tests done to find out about low oxygen. Back in the summer of 2021. Nothing found causing it at that time. In Mar2022 got new doctor and told her about the oxygen problem. She also found that it had a higher-than-normal heart rate. She was advised to see a Cardiologist. He ordered more test again CTA, Echo, EKG's, Heart monitor. Just All the tests were done and would be seeing him again for information. Patient was not sure of when all of this started. Found out problem when she visited by new Doctor. They also reviewed all her tests done.  Follow-Up (18Aug2022): Follow-up attempts are completed. No further information is expected.  Follow-up (30Aug2022): This is a spontaneous follow-up report received from a contactable consumer. This consumer reported in response to Non-HCP letter sent. Updated information included: Relevant Medical History, Past drug and concomitant medication added. Lab tests related to events added. Vaccine start time and Route of administration added. Event (Low oxygen level) added. Event onset time for AE (Inappropriate schedule of vaccine administered) and clinical information updated.  Follow-up attempts are completed. No further information is expected.