Hypoxia; anemia; tachycardia; decreased red blood cell count; decreased hematocrit; low iron; very low ferritin level; This is a spontaneous report received from contactable reporter(s) (Other HCP). The reporter is the patient.  A 74-year-old female patient (not pregnant) received BNT162b2 (BNT162B2), on 01Mar2021 as dose 2, single (Lot number: EN6203) at the age of 74 years, in left arm for covid-19 immunization. The patient's relevant medical history included: "Known allergies: sulfa medications" (unspecified if ongoing). Concomitant medication(s) included: PREMARIN; POSTURE D [CALCIUM PHOSPHATE;COLECALCIFEROL;ERGOCALCIFEROL]; D3. Vaccination history included: BNT162b2 (Dose Number: 1, Batch/Lot No: EL9262, Location of injection: Arm Left), administration date: 08Feb2021, when the patient was 74-year-old, for COVID-19 immunization. The following information was reported: HYPOXIA (medically significant) with onset 29May2021, outcome "recovered with sequelae"; ANAEMIA (non-serious) with onset 29May2021, outcome "recovered with sequelae", described as "anemia"; HAEMATOCRIT DECREASED (non-serious) with onset 29May2021, outcome "recovered with sequelae", described as "decreased hematocrit"; RED BLOOD CELL COUNT DECREASED (non-serious) with onset 29May2021, outcome "recovered with sequelae", described as "decreased red blood cell count"; BLOOD IRON DECREASED (non-serious) with onset 29May2021, outcome "recovered with sequelae", described as "low iron"; TACHYCARDIA (non-serious) with onset 29May2021, outcome "recovered with sequelae"; SERUM FERRITIN DECREASED (non-serious) with onset 29May2021, outcome "recovered with sequelae", described as "very low ferritin level". The events "hypoxia", "anemia", "tachycardia", "decreased red blood cell count", "decreased hematocrit", "low iron" and "very low ferritin level" required physician office visit. The patient underwent the following laboratory tests and procedures: Blood iron: (2021) Low; Haematocrit: (2021) decreased; Red blood cell count: (2021) decreased; SARS-CoV-2 test: (22Dec2021) Negative, notes: Nasal Swab; Serum ferritin: (2021) Very low. Therapeutic measures were taken as a result of hypoxia, anaemia, tachycardia, red blood cell count decreased, haematocrit decreased, blood iron decreased, serum ferritin decreased.  Clinical course: Adverse event: Hypoxia, anemia, tachycardia, decreased red blood cell count, decreased hematocrit, low iron, and very low ferritin level. The symptoms, confirmed with blood testing, occurred twice. Once 2.5 months after the second shot, and again 5.5 months after the third shot. In addition, after the third shot there were periodic skin irritations with itching and non-specific patchy dermatoses. Patient received treatment Slow Fe for 45 days on the first episode, No covid prior vaccination.; Sender's Comments: Based on the current available information and the plausible drug-event temporal association, a possible contributory role of the suspect product BNT162B2 to the hypoxia cannot be excluded. 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.