I. To characterize CMV reactivation and CMV disease in recipients of CMV-MVA Triplex compared to placebo by assessing time-to viremia (defined as number of days from transplantation to the date of > 500 CMV gc/mL), duration of viremia, recurrence of viremia, incidence of late CMV viremia/disease (> 100 and =< 360 days post HCT), use of antiviral drugs (triggered by clinically significant viremia of >= 1500 CMV gc/mL), cumulative number of CMV specific antiviral treatment days.