Subacute-Onset Anemia Following COVID-19 Vaccine Combination with ChAdOx (AstraZeneca) and BNT162b2 (BioNTech, Pfizer)—A Case Report

Background and Clinical Significance: The COVID-19 pandemic led to the rapid development of effective vaccination strategies. Although COVID-19 vaccines are generally safe, rare hematological adverse events have been reported, most prominently vaccine-induced immune thrombotic thrombocytopenia (VITT). Isolated cases of autoimmune cytopenias and bone marrow failure syndromes following COVID-19 vaccination have also been described. Case Presentation: We report the case of an 80-year-old male who developed subacute-onset severe normocytic anemia with reticulocytopenia and mild leukopenia following heterologous COVID-19 vaccination with ChAdOx1 nCoV-19 (AstraZeneca) and BNT162b2 (Pfizer–BioNTech). Seven days after the second vaccination, mild anemia was detected, progressing over the following weeks to symptomatic anemia requiring hospitalization. Extensive diagnostic evaluation revealed no evidence of hemolysis, nutritional deficiency, autoimmune disease, or viral infection, including SARS-CoV-2 and Parvovirus B19. Bone marrow examination demonstrated an erythroid maturation arrest at the proerythroblast stage, resembling a pure red cell aplasia (PRCA)-like pattern. Cytogenetic and molecular analyses excluded myelodysplastic syndromes. Treatment with erythropoietin resulted in complete hematologic recovery. Conclusions: This case suggests that, in rare instances, COVID-19 vaccination may be temporally associated with transient suppression of erythropoiesis. Further studies are required to elucidate underlying mechanisms and to guide diagnosis and management.