Probable warm autoimmune hemolytic anemia; The initial case was missing the following minimum criteria: [ICH-unidentifiable patients]. Upon receipt of follow-up information on [15Nov2022], this case now contains all required information to be considered valid.  This is a literature report for the following literature source(s):   A 70-year-old male patient received BNT162b2 (BNT162B2), on 13Feb2021 as dose 2, single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history included: "hypothyroidism" (ongoing); "obstructive sleep apnea" (unspecified if ongoing); "hypertension" (ongoing); "type 2 diabetes" (ongoing); "gastroesophageal reflux disease" (unspecified if ongoing); "testosterone deficiency" (unspecified if ongoing); "brown urine" (unspecified if ongoing). The patient's concomitant medications were not reported. Past drug history included: Cephalexin for presumed urinary tract infection, reaction(s): "his condition continued to worsen". Vaccination history included: BNT162b2 (DOSE 1, SINGLE), administration date: 22Jan2021, for COVID-19 IMMUNIZATION.  The following information was reported: AUTOIMMUNE HAEMOLYTIC ANAEMIA (hospitalization, medically significant), outcome "unknown", described as "Probable warm autoimmune hemolytic anemia". The patient underwent the following laboratory tests and procedures: Antibody test: (2021) positive, notes: both a warm autoantibody and cold autoantibody were identified; Blood bilirubin (normal high range 12): (2021) 3.2 mg/ml; Blood immunoglobulin G: (2021) positive; Blood smear test: (2021) was suggestive of hemolysis, notes: with a moderate erythrocyte microcytosis and polychromasia; Coombs direct test: (2021) Positive; Coombs indirect test: (2021) positive; Haemoglobin (13.2-16.6): (19Feb2021) 6.3 g/dl; (26Apr2021) 15.6 g/dl, notes: 2 days after his admission; (2021) Hb slowly trendedup but not significantly; (2021) Hb was finally stable; Haptoglobin (20-300): (2021) 20 mg/dl; anti-immunoglobulin G (IgG) reagents: (2021) Positive, notes: a positive anti-IgG is deemed adequate to suggest hemolytic anemia; Lactase deficiency (140-280): (2021) 688 IU/l; Reticulocyte count (0.5-2.5): (2021) 7.6 %. Therapeutic measures were taken as a result of autoimmune haemolytic anaemia.  Clinical course: It was reported that, two days before his admission, he was seen at an urgent care facility with a chief complaint of brown urine and was prescribed cephalexin for a presumed urinary tract infection. However, his condition continued to worsen, and he eventually visited his primary care physician. His direct antiglobulin test (DAT) was positive, with both polyspecific antihuman globulin (AHG) and anti-immunoglobulin G (IgG) reagents, and he was diagnosed with probable WAIHA. The patient denied any previous episodes of anemia and had never required a blood transfusion; he also denied any hematochezia, hematuria, epistaxis, gum bleed, or hematemesis. The patient did not have any prior COVID-19 infection. Of note, he had received the first dose of Pfizer COVID-19 vaccine on 22Jan2021, approximately 3 months before admission, and had not experienced any adverse effects at that time. His hemoglobin (Hb) level dropped from 15.6 g/dL on 19Feb2021 (6 days after the second dose of COVID-19 vaccine) to a nadir of 6.3 g/dL, 2 days after his admission on 26Apr2021 (Hb normal range 13.2 16.6 g/dL). On admission, other lab values were as follows: lactase dehydrogenase 688 U/L (normal range 140 280 U/L), bilirubin 3.2 mg/dL (normal <1.2 mg/dL), and reticulocytes 7.6 percent (normal range 0.5 2.5%). Peripheral blood smear was suggestive of hemolysis, with a moderate erythrocyte microcytosis and polychromasia. A haptoglobin test was ordered that showed levels below 20 mg/dL (normal range 30 200 mg/dL). In addition, his antibody detection test was positive; both a warm autoantibody and cold autoantibody were identified. DATs with both polyspecific AHG and anti-IgG were positive. However, the blood bank did not perform anti-C3 testing or an eluate because a positive DAT with both polyspecific AHG and anti-IgG is deemed adequate to suggest hemolytic anemia. During his hospitalization, the patient was started on intravenous methylprednisolone succinate (125 mg/mL every 8 hours, with 80 mg intravenous methylprednisolone). Blood transfusion was suggested if his Hb dropped below 7 g/dL however, no transfusions were ordered. His Hb slowly trended up but not significantly; consequently, rituximab was started. He was discharged with orders for 120 mg of steroids daily and one rituximab injection weekly. Over the next few weeks, the patient continued with the steroids and rituximab until his Hb was finally stable.; Sender's Comments: Based on the available information in the case, the causal association between the event 'autoimmune hemolytic anemia' and the suspect drug BNT162B2 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.