A Case of Coomb’s Negative Hemolysis Post-mRNA COVID-19 Vaccine in a Patient With Polycythemia Vera

Acquired hemolytic anemias have various causes, including autoimmune hemolysis, and can be triggered by vaccines, infections, or medications. Our patient experienced a serious case of transient hemolytic anemia following the mRNA-1273 COVID-19 vaccine. A 69-year-old male with hypertension, gastroesophageal reflux disease, and polycythemia vera (JAK2 V617F mutation) presented with worsening fatigue. He had been taking aspirin and hydroxyurea since 2015 and had a history of oral-genital herpes simplex viral ulcers treated with as-needed acyclovir. Thirteen days prior to presentation, the patient had received his second dose of the COVID-19 vaccine. On examination, the patient appeared pale and denied any noticeable blood loss or dark, tarry stools. Laboratory tests showed a significant drop in hemoglobin from 11.4 mg/dL at his previous visit to 5.9 mg/dL. His reticulocyte count was elevated at 6.15%, haptoglobin was undetectable, and lactate dehydrogenase (LDH), which had been normal three months earlier, had risen to 252 U/L. Urinalysis and total bilirubin levels were normal. Investigations for common causes of hemolysis were negative, and the peripheral blood smear revealed polychromasia, mild Rouleaux formation, and no significant red blood cell (RBC) fragments. The clinical concern was for an immune-mediated but Coombs-negative hemolytic reaction triggered by the COVID-19 vaccine. Hydroxyurea was held, and the patient’s hemoglobin gradually improved over the next month without the need for RBC transfusions. His LDH, haptoglobin levels, and reticulocyte count returned to baseline. The patient was restarted on hydroxyurea and experienced no further episodes of hemolysis. While there are reports of hemolysis following COVID-19 vaccination, especially in conditions like paroxysmal nocturnal hemoglobinuria, thrombotic thrombocytopenic purpura, and hereditary spherocytosis, we found no cases linking hemolysis to polycythemia vera or hydroxyurea therapy. This case highlights the importance of monitoring vaccine-related complications in patients with hematologic conditions. Categories: Internal Medicine, Infectious Disease, Hematology