Epidemiology and clinical characteristics of pandemic (H1N1) 2009 influenza infection in pediatric hemato-oncology and hematopoietic stem cell transplantation patients.

ABSTRACT

BACKGROUND: For children with hemato-oncologic diseases, especially after hematopoietic stem cell transplantation (HSCT), the risk for developing complications related to pandemic influenza A (H1N1) 2009 (pH1N1) infection is largely unknown. METHODS: A retrospective chart study was performed of pH1N1 cases diagnosed between October 2009 to January 2010 in the hemato-oncologic unit of the University Children's Hospital of Düsseldorf, Germany. FINDINGS: In total, 21 children were diagnosed with laboratory-confirmed pH1N1; in 16 patients with malignancies (acute leukemia 7, lymphoma 4, solid tumors 2, others 3) and in 5 with benign hematologic disorders. Five patients had undergone prior HSCT, although 1 patient was diagnosed during conditioning therapy with high-dose chemotherapy in preparation for haploidentical HSCT. Most frequent symptoms were fever (>38.5°C) and cough (in 100%), and rhinorrhea (57%). The 2 patients acquiring pH1N1 infection under high-dose or intensive chemotherapy did not require intensive care or mechanical ventilation, and both recovered under antiviral therapy. Oseltamivir was administered to 11 patients; in 1 patient, therapy was switched, on a compassionate-use basis, to intravenous zanamivir because of lack of clinical improvement after oseltamivir therapy. Complications were hospitalization (19%), demand of oxygen supplementation, delay/interruption of antineoplastic therapy, and prolonged administration of antibiotics and antipyretics. CONCLUSION: In the investigated patient population, pH1N1 was mild in most cases, but was associated with substantial morbidity in a proportion of patients and led to interruption and delay in anticancer treatment.