The main inclusion criteria include but are not limited to the following: - Is a recipient of a primary or secondary allograft kidney - Is at least 4 weeks posttransplant and not more than 52 weeks posttransplant at the time of enrollment (Day 1) and is being managed per local standard of care - Has stable kidney function posttransplant - Has undetectable CMV deoxyribonucleic acid (DNA) from a plasma or whole blood sample collected within 14 days prior to enrollment - Must be able to take (as assessed by the investigator) letermovir tablets or oral pellets by mouth, or via gastrostomy or nasogastric tube (oral pellets only) - Does not have a condition that may interfere with the absorption of oral medication (e.g., vomiting, diarrhea, or a malabsorptive condition) from the day of enrollment (Day 1) until the intensive pharmacokinetics (IPK) sampling is completed - Weighs ≥2.5 and <40 kg at enrollment (Day 1)

The main exclusion criteria include but are not limited to the following: - Has CMV disease or suspected CMV disease between screening and enrollment - Is on dialysis or plasmapheresis at the time of enrollment - Has evidence of CMV viremia at any time from screening until the time of enrollment - Has Child-Pugh B or C hepatic insufficiency within 14 days before enrollment - Is a multi-organ transplant recipient (e.g., kidney-pancreas) - Has any uncontrolled infection on the day of enrollment - Requires mechanical ventilation, or is hemodynamically unstable, at the time of enrollment - Has received or is receiving protocol-specified prohibited medications