1. North-Western Tuscany Blood Bank, Pisa University Hospital , Pisa , Italy
2. Division of Hematology and Transfusion Medicine, Carlo Poma Hospital , Mantua , Italy
3. Division of Infectious Diseases, National Institute for Infectious Diseases “Lazzaro Spallanzani,” Rome , Italy
4. Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health , Baltimore, Maryland , USA