['prevention of cmv infection or disease']
['letermovir', 'placebo']

        Inclusion Criteria:

          -  Has documented seropositivity for CMV within 1 year before hematopoietic stem cell
             transplant (HSCT)

          -  Receiving first allogeneic HSCT (bone marrow, peripheral blood stem cell, or cord
             blood transplant)

          -  Female or male participant who is not of reproductive potential, or, if of
             reproductive potential, agrees to true abstinence or to use (or have their partner
             use) 2 acceptable methods of birth control from the time of consent through 90 days
             after the last dose of study drug

          -  Able to read, understand, and complete questionnaires and diaries

        Exclusion Criteria:

          -  Received a previous allogeneic HSCT (previous autologous HSCT is acceptable)

          -  History of CMV end-organ disease within 6 months before randomization

          -  Has evidence of CMV viremia (if tested) at any time from either signing of the
             Informed Consent Form or the HSCT procedure, whichever is earlier, until the time of
             randomization.

          -  Received the following within 7 days before screening or plans to receive during the
             study: ganciclovir, valganciclovir, foscarnet, acyclovir, valacyclovir, or famciclovir

          -  Received the following within 30 days before screening or plan to receive during the
             study: cidofovir, CMV hyper-immune globulin, any investigational CMV antiviral agent
             or biological therapy

          -  Has suspected or known hypersensitivity to ingredients of MK-8228 (letermovir)
             formulations

          -  Has severe hepatic insufficiency within 5 days before randomization

          -  Has end-stage renal impairment

          -  Has an uncontrolled infection on the day of randomization

          -  Requires mechanical ventilation or is hemodynamically unstable at the time of
             randomization

          -  Has documented positive results for human immunodeficiency virus (HIV) antibody,
             hepatitis C virus (HCV) antibody with detectable HCV ribonucleic acid, or hepatitis B
             surface antigen (HBsAg) within 90 days before randomization

          -  Has active solid tumor malignancies with the exception of localized basal cell or
             squamous cell skin cancer or the condition under treatment (for example, lymphoma)

          -  Is pregnant or expecting to conceive, is breastfeeding, or plans to breastfeed from
             the time of consent through 90 days after the last dose of study drug

          -  Is expecting to donate eggs or sperm from the time of consent through 90 days after
             the last dose of study drug

          -  Has participated in a study with an unapproved investigational compound (monoclonal
             antibodies are excepted) or device within 28 days of the first dose of study drug

          -  Has previously participated in a MK-8228 (letermovir) study

          -  Has, is, or is planning (during the study) to participate in any study involving
             administration of a CMV vaccine or another CMV investigational agent

          -  Is a user of recreational or illicit drugs or has a recent history (<=1 year) of drug
             or alcohol abuse or dependence
      