The purpose of this study is to compare the pharmacokinetics (PK), safety, and tolerability of maribavir administered as a single oral dose in healthy, adult participants of Japanese descent and matched, healthy, adult, non-Hispanic, Caucasian participants. In addition, this study will assess the dose-proportionality of PK of maribavir in healthy, adult participants of Japanese descent.

The study will be conducted in two cohorts, Cohort A and Cohort B. Cohort A consists of 12 participants of Japanese Descent. Cohort B consists of 12 non-Hispanic, Caucasian participants.

For Japanese participants there will be three treatment periods. In Treatment Period 1, they will receive maribavir as a single 400 mg oral dose. In Treatment Periods 2 and 3, all Japanese participants will receive maribavir as a single oral dose of either 200 mg or 800 mg, depending upon randomization assignment. For the non-Hispanic, Caucasian group there will be only one treatment period and they will receive maribavir as a single 400 mg oral dose.

Inclusion Criteria:

• An understanding, ability, and willingness to fully comply with study procedures and restrictions.
• Ability to voluntarily provide written informed consent/assent as applicable to participate in the study.
• Healthy 18 to 55 years old participants of Japanese descent and non-Hispanic Caucasian origin.
• Healthy participants of Japanese descent must have been born in Japan and must not have lived outside of Japan for greater than (>) 10 years; both parents and all 4 grandparents must be of Japanese origin. Healthy, non-Hispanic, Caucasian participants must have both parents and all 4 grandparents of non-Hispanic, Caucasian origin.
• Male, or non-pregnant, non-breastfeeding female who agrees to comply with any applicable contraceptive requirements of the protocol or females of non-childbearing potential.
• Hemoglobin for males greater than or equal to (>=) 135.0 gram per liter (g/L) and females >= 120.0 g/L at screening and on Day -1.
• Body mass index (BMI) between 18.5 and 28.0 kilogram per square meter (kg/m^2) inclusive with a body weight > 45 kilograms (kg) (99 pounds [lbs]).
• Ability to swallow a dose of investigational product (IP).

Exclusion Criteria:

• History of any hematological, hepatic, respiratory, cardiovascular, renal, neurological, or psychiatric disease, gall bladder removal, or current recurrent disease.
• Current or relevant history of physical or psychiatric illness, any medical disorder that may require treatment or make the participant unlikely to fully complete the study, or any condition that presents undue risk from the IP or procedures.
• Known or suspected intolerance or hypersensitivity to maribavir, closely-related compounds, or any of the stated ingredients.
• Significant illness, as judged by the investigator, within 2 weeks of the first dose of IP.
• Donation of blood or blood products (e.g. plasma or platelets) within 60 days prior to receiving the first dose of IP.
• Have taken another IP within 30 days or five half-lives of that IP, whichever is greater, prior to the first dose of maribavir.
• Have been enrolled in a clinical study (including vaccine studies) within 30 days prior to the first dose of IP that, in the investigator's opinion, may impact this study.
• Have had any substantial changes in eating habits within 30 days prior to the first dose of IP, as assessed by the investigator.
• Confirmed systolic blood pressure > 139 millimeter of mercury (mmHg) or less than (<) 89 mmHg, and diastolic blood pressure > 89 mmHg or < 49 mmHg.
• Twelve-lead ECG demonstrating QTc > 450 milliseconds (msec).
• Known history of alcohol or other substance abuse, including synthetic cannabinoids within the last year.
• Male participants who consume more than 21 units of alcohol per week or 3 units per day. Female participants who consume more than 14 units of alcohol per week or 2 units per day.
• A positive urine test for drugs of abuse, alcohol, or cotinine at screening or on Day -1.
• A positive human immunodeficiency virus (HIV), hepatitis B surface antibody (HBsAg), or hepatitis C virus (HCV) antibody screen.
• Use of tobacco in any form (e.g. smoking or chewing) or other nicotine-containing products in any form (e.g. gum, patch).
• Routine consumption of more than 2 units of caffeine per day or participants who experience caffeine withdrawal headaches.
• Current use of any prescription medication within 30 days of the first dose of IP. Current use of any over the counter medication within 14 days of the first dose of IP.
• Ingestion of known cytochrome P450 (CYP) 3A modulators within 7 days of Day 1, period 1
• History of active or chronic oral/nasal cavity infections, gastroesophageal reflux, asthma treatment with albuterol, zinc supplementation.
• Participants with dry mouth syndrome or burning mouth syndrome or menopausal women suffering from dysgeusia.
• Participants who have acute gastrointestinal (GI) symptoms at screening or admission (e.g. nausea, vomiting, diarrhea, and heartburn).

De-identified individual participant data from this particular study will not be shared as the data are subject to contractual (or consent) provisions that prohibit transfer to third parties.