In sum, the incidence of EBV infection will be adequately measured during a 1-year follow-up period. In all sites, AT LEAST 1 EBV PCR test is done per 1-2 weeks during hospitalization, 2 EBV PCR tests per month from hospital discharge to 6 months post-transplantation and approximately 1 EBV PCR test per month from 6 months to 12 months. The total number of EBV PCR results that will be collected per patient for the entire follow-up will be approximately 18. These results will be retrieved from patient charts.