NCT07214571From ClinicalTrials.govRecruiting

A Study of S-337395 in Symptomatic Nonhospitalized Adults With Respiratory Syncytial Virus (RSV) Who Are at High Risk of Progression to Severe Disease

A Phase 2b, Multicenter, Randomized, Double-blind, Placebo-controlled, Parallel-group Study to Evaluate the Safety, Tolerability, and Efficacy of S-337395 in Symptomatic Nonhospitalized Adults With Respiratory Syncytial Virus Who Are at High Risk of Progression to Severe Disease

Respiratory Syncytial Virus Infections

At a glance

Phase: Phase 2
Study type: Interventional
Sponsor: Shionogi
Enrolment target: 192
Started: 11 December 2025
Main results due: 30 December 2026
Study sites: 87
Registry updated: 29 September 2026

Can you take part?

Aged 18 years and over.
Open to any sex.
You need the condition being studied — healthy volunteers are not accepted.

These are the headline rules only. Every study has a longer list, and whether you are eligible is decided by the research team at the site — never by this page.

Read the full eligibility criteria

Key Inclusion Criteria:

* Participants who have new onset or worsening (if present chronically) of at least 1 of the following signs and/or symptoms consistent with a viral acute respiratory infection within 72 hours prior to randomization: fever, nasal congestion, nasal discharge, sore throat, cough, sputum production, shortness of breath, or wheezing.
* Participants diagnosed with RSV infection preferably using a rapid polymerase chain reaction (PCR) or other molecular-based diagnostic assay.
* Has at least 1 of the following risk factors for severe RSV disease:

1. ≥ 75 years of age;
2. Chronic lung disease that is symptomatic and requiring chronic treatment; and
3. Chronic cardiovascular disease that is symptomatic and requiring chronic treatment.
* With the exception of the RSV disease, medically stable on the basis of medical history, physical examination, vital signs, and 12-lead electrocardiogram (ECG) performed at screening.

Key Exclusion Criteria:

* Hospitalized or expected to be hospitalized within 24 hours of screening.
* Is considered by the investigator to be immunocompromised, due to an underlying medical condition or medical therapy, chemotherapy, radiation, stem cell or solid organ transplant.
* Has known allergies, hypersensitivity, or intolerance to S-337395 or to any of the excipients of the S-337395 or placebo formulation.
* Suspicion or known severe renal impairment.
* Any other medical or psychiatric condition making the participant unsuitable for the current study or interfering with the evaluation of response to the study intervention in the opinion of the investigator/subinvestigator.
* Has received a therapy intended to treat RSV infection within 14 days prior to screening.
* Is receiving chemotherapy or immunotherapy for malignancy.
* Has received RSV vaccination within 7 days prior to screening.
* Has had either confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or influenza infection (test was positive) during the 28 days prior to screening.
* Has any other confirmed clinically relevant respiratory infection by any pathogen at, or within 28 days of screening.

Note: Other protocol-specified inclusion and exclusion criteria may apply.

What this study is about

In the sponsor’s own words, from the registry.

The main purpose of this study is to investigate the antiviral effect of S-337395 compared with placebo among nonhospitalized adult participants with high-risk factors for progression to severe RSV infection starting intervention within 72 hours of RSV symptom onset.

Study sites(87)

LA Universal Research Center, Inc.
Los Angeles, California, United States
Recruiting
Central Valley Research
Modesto, California, United States
Recruiting
Med Partnes, Inc - Elligo- PPDS
Toluca Lake, California, United States
Recruiting
Hope Clinical Trials - 3970 W Flagler St.
Coral Gables, Florida, United States
Recruiting
Beautiful Minds Clinical Research Center
Cutler Bay, Florida, United States
Recruiting
Doral Medical Research
Hialeah, Florida, United States
Recruiting
Southern Clinical Research
Miami, Florida, United States
Recruiting
LCC Medical Research - Miami - BTC - PPDS
Miami, Florida, United States
Recruiting
Global Health Clinical Trials
Miami, Florida, United States
Recruiting
Nuren Medical and Research Center
Miami, Florida, United States
Recruiting
Continental Clinical Research, LLC
Miami, Florida, United States
Recruiting
Dynamic Medical Research, LLC - Miami
Miami, Florida, United States
Withdrawn
Miami Clinical Research, LLP.
Miami, Florida, United States
Recruiting
Reed Medical Research
Miami, Florida, United States
Recruiting
Palm Springs Community Health Center
Miami Lakes, Florida, United States
Recruiting
Oceanic Research Group, LLC
North Miami Beach, Florida, United States
Recruiting
CDC Research Institute, LLC
Port Saint Lucie, Florida, United States
Recruiting
Cordova Research Insittute
Sweetwater, Florida, United States
Recruiting
Better Life Clinical Research LLC
Tampa, Florida, United States
Recruiting
Research Bay,Inc.
Tampa, Florida, United States
Recruiting
Santos Research Center - 5927 Webb Rd
Tampa, Florida, United States
Recruiting
Angels Clinical Research Institute Tampa-Palm Springs
Tampa, Florida, United States
Recruiting
Covenant Pulmonary Criticial Care and Research Ins
East Point, Georgia, United States
Recruiting
Beth Israel Deaconess Medical Center
Boston, Massachusetts, United States
Recruiting
University of Massachusetts
Worcester, Massachusetts, United States
Recruiting
Clay Platte Family Medicine - CCT Research
Kansas City, Missouri, United States
Recruiting
NYC Health + Hospitals/Lincoln Medical Center - BRANY - PPDS
The Bronx, New York, United States
Recruiting
Prime Global Research, Inc.
The Bronx, New York, United States
Recruiting
Progressive Medicine of the Triad, LLC
Winston-Salem, North Carolina, United States
Recruiting
University Hospitals Cleveland Medical Center
Cleveland, Ohio, United States
Recruiting
Epic Medical Research - Chickasha
Chickasha, Oklahoma, United States
Recruiting
Rhode Island Hospital
Providence, Rhode Island, United States
Recruiting
Epic Med. Research LLC, DeSoto
DeSoto, Texas, United States
Recruiting
DCT-McAllen Primary Care Research, LLC
McAllen, Texas, United States
Recruiting
SMS Clinical Research, LLC - 400 W. Kearney St
Mesquite, Texas, United States
Recruiting
Clinical Research Partners LLC
Richmond, Virginia, United States
Recruiting
Frontier Clinical Research Waterfront
Morgantown, West Virginia, United States
Recruiting
Fundación Huésped - PPDS
CABA, Buenos Aires, Argentina
Recruiting
AES - AS - Glenny Corp. S.A. Buenos Aires
CABA, Buenos Aires, Argentina
Recruiting
CEMLO - Centro de Especialidades Médicas
Lobos, Buenos Aires, Argentina
Recruiting
Instituto De Enfermedades Respiratorias E Investigación Médica - IERIM
San Juan Bautista, Buenos Aires, Argentina
Recruiting
Instituto Médico Río Cuarto
Río Cuarto, Córdoba Province, Argentina
Recruiting
AES - AS - Clinica Mayo de Urgencias
San Miguel de Tucumán, Tucumán Province, Argentina
Recruiting
Medical Center Hera EOOD, Montana
Montana, Sofia, Bulgaria
Recruiting
Multiprofile Hospital For Active Treatment Dr Tota Venkova - PRATIA - PPDS
Gabrovo, Bulgaria
Recruiting
MCpulmo-2018 Ltd
Haskovo, Bulgaria
Recruiting
Medical Center Hera EOOD
Sofia, Bulgaria
Recruiting
Medical Center Neuromedics EOOD - 4 Veliki Preslav Str
Veliko Tarnovo, Bulgaria
Recruiting
Kamezawa Clinic
Kasugai-Shi, Aiti, Japan
Recruiting
Hosokawa Surgical Clinic
Nagoya-Shi Nakamura-Ku, Aiti, Japan
Recruiting
Doi Clinic
Chikushino-shi, Fukuoka, Japan
Recruiting
Irie Clinic
Fukuoka, Fukuoka, Japan
Recruiting
Tomita Internal Medicine Clinic
Fukuoka-Shi Chuo-Ku, Fukuoka, Japan
Recruiting
PS Clinic
Fukuoka-Shi Hakata-Ku, Fukuoka, Japan
Recruiting
Medical corporation Aimeikai Morizono internal medicine
Kitakyushu-Shi Yahatanishi-Ku, Fukuoka, Japan
Recruiting
Social Medical Corporation the Chiyukai foundation Shin Komonji Hospital
Kitakyushu-Shi, Fukuoka, Japan
Recruiting
Shizuka Clinic
Takasaki-shi, Gunma, Japan
Recruiting
Social medical corporation Keiwakai Nishioka Hospital
Sapporo-Shi Toyohira-Ku, Hokkaidô, Japan
Recruiting
Terada Internal Medicine and Respiratory Department
Himeji-shi, Hyôgo, Japan
Recruiting
Tsuchiura Beryl Clinic
Tsuchiura-Shi, Ibaraki, Japan
Recruiting

Showing 60 of 87 sites — filter to narrow it down. 86 of the 87 sites on this study are recruiting right now — a site can stop enrolling while the study as a whole is still open.

Source: ClinicalTrials.gov record NCT07214571. Trialion does not run this study, is not paid to refer anyone to it, and cannot enrol you. Eligibility is always decided by the research team at the site.

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