Severe HCoV‐OC43 Pneumonia in a 25‐Year‐Old Woman Following Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND: We report the case of a 25-year-old woman with a history of acute lymphoblastic leukemia who developed progressive dyspnea and fever following allogeneic hematopoietic stem cell transplantation. CASE PRESENTATION: Despite broad-spectrum empirical antimicrobial therapy, the patient's clinical condition worsened. Comprehensive diagnostic evaluation revealed human coronavirus OC43 (HCoV-OC43) as the causative pathogen. Histopathological examination of lung tissue confirmed viral pneumonia. Treatment with nirmatrelvir/ritonavir (Paxlovid) was initiated. The patient demonstrated rapid clinical improvement, with complete radiological resolution within 3 months. CONCLUSION: This case highlights the potential therapeutic role of nirmatrelvir/ritonavir in managing severe HCoV-OC43 pneumonia in patients who are immunocompromised.