A Study of JNJ-64281802 for the Prevention of Dengue Infection

A Phase 2, Randomized, Double-blind, Placebo-controlled, Double-dummy, Multicenter Trial Assessing the Efficacy and Safety of Two Dose Regimens of JNJ-64281802 for the Prevention of Dengue Infection

The purpose of this study is to evaluate the prophylactic effect of JNJ-64281802 with respect to the prevention of laboratory-confirmed dengue virus (DENV) infection up to the last day of dosing among participants who have no evidence of current DENV infection at baseline.

Participants will receive JNJ-64281802 400 milligrams (mg) loading dose (LD) twice daily for 48 hours (2 days), followed by JNJ-64281802 150 mg maintenance dose (MD) once daily for 26 days in fed conditions.

Participants will receive JNJ-64281802 150 mg LD twice daily for 48 hours (2 days), followed by JNJ-64281802 50 mg MD once daily for 26 days in fed conditions.

Number of Participants with Laboratory-confirmed Dengue Virus (DENV) Infection Between Baseline and the Last Day of Dosing Among Participants Who Have No Evidence of Current DENV Infection at Baseline

Number of participants with laboratory-confirmed DENV infection between baseline and the last day of dosing among participants who have no evidence of current DENV infection at baseline will be reported. Presence of a laboratory-confirmed DENV infection is defined as a positive DENV ribonucleic acid (RNA) or DENV nonstructural (NS)1 protein test result.

Number of Participants with Laboratory-confirmed Symptomatic DENV Infection Between Baseline and the Last Day of Dosing Among All Participants

Number of participants with laboratory-confirmed symptomatic DENV infection between baseline and the last day of dosing among all participants will be reported. Laboratory-confirmed symptomatic DENV infection is defined as having at least 2 solicited systemic adverse events (AEs), of which at least one is a most common dengue symptom (that is, fever, headache/retro-orbital pain, myalgia, arthralgia, rash), lasting for greater than or equal to (>=) 1 day and occurring within a plus/minus (+/-) 2 days time window around the positive polymerase chain reaction (PCR) or NS1 test, between baseline and the last day of dosing.

Number of Participants with Laboratory-confirmed Symptomatic DENV Infection Between Baseline and the Last Day of Dosing Among Participants With No Evidence of Current DENV Infection at Baseline

Number of participants with laboratory-confirmed symptomatic DENV infection between baseline and the last day of dosing among participants who have no evidence of current DENV infection at baseline will be reported.

An AE is any untoward medical occurrence in a participant participating in a clinical study that does not necessarily have a causal relationship with the pharmaceutical/ biological agent under study.

SAE is any untoward medical occurrence that at any dose results in any of the following outcomes: death; initial or prolonged inpatient hospitalization; life-threatening experience (immediate risk of dying); persistent or significant disability/incapacity; congenital anomaly/birth defect; suspected transmission of any infectious agent via a medicinal product or medically important.

Number of participants with abnormalities in physical examinations (including examination of head/neck/thyroid, eyes/ears/nose/throat, respiratory, cardiovascular, lymph nodes, abdomen, skin, musculoskeletal, and neurological body systems) will be reported.

Number of participants with abnormalities in vital signs (including temperature, pulse or heart rate, blood pressure [systolic and diastolic]) will be reported.

Number of participants with abnormalities in clinical laboratory assessments (serum chemistry, hematology and coagulation, and urinalysis) will be reported.

Observed JNJ-64281802 Concentration Just Prior to the Beginning or at the End of a Dosing Interval (Ctrough)

Ctrough is defined as observed plasma concentration of JNJ-64281802 just prior to the beginning or at the end of a dosing interval.

Inclusion Criteria: Healthy on the basis of physical examination, medical history, and vital signs performed at screening. If there are abnormalities, the participant may be included only if the investigator judges the abnormalities to be not clinically relevant. This determination must be recorded in the participant's source documents Must have a body mass index (BMI, weight in kilogram [kg] divided by the square of height in meters) between 18.0 and 35.0 kilograms per meter square (kg/m^2) inclusive, and a body weight of greater than or equal to (>=) 40.0 kg at screening A woman must have a negative highly sensitive urine pregnancy test at screening A male participant must agree not to donate sperm for the purpose of reproduction during the study and for >= 90 days after receiving the last dose of study intervention Must sign an informed consent form (ICF) (or their legally acceptable representative must sign) indicating that the participant understands the purpose of, and procedures required for, the study and is willing to participate in the study Exclusion Criteria: Having any dengue virus (DENV)-associated clinical signs and symptoms Known allergies, hypersensitivity, or intolerance to JNJ-64281802 or its excipients Any clinically relevant skin disease (as assessed by the investigator) in the past 3 months such as, but not limited to, dermatitis, eczema, drug rash, psoriasis, food allergy, and urticaria Reduced immune function to be: (a) Known or suspected congenital or acquired immunodeficiency; or (b) receipt of immunomodulation therapy within the last 6 months (such as anticancer chemotherapy or radiation therapy) Received an investigational intervention (including investigational vaccines other than a corona virus disease 2019 [COVID-19] vaccine) or used an invasive investigational medical device within 3 months before the planned first dose of study intervention or received an investigational biologic product within 3 months prior to enrollment or 5 half-lives, whichever is longer, before the planned first dose of study intervention, or is currently enrolled in an investigational study

The data sharing policy of the Janssen Pharmaceutical Companies of Johnson & Johnson is available at www.janssen.com/clinical-trials/transparency. As noted on this site, requests for access to the study data can be submitted through Yale Open Data Access (YODA) Project site at yoda.yale.edu