NCT07214571 · Shionogi
A Study of S-337395 in Symptomatic Nonhospitalized Adults With Respiratory Syncytial Virus (RSV) Who Are at High Risk of Progression to Severe Disease
What this study is about
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.
View original scientific description
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.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
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:
- ≥ 75 years of age;
- Chronic lung disease that is symptomatic and requiring chronic treatment; and
- 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.
Where
- Los Angeles, California
- Toluca Lake, California
- Coral Gables, Florida
- Cutler Bay, Florida
- Hialeah, Florida
- Miami, Florida
- Miami Lakes, Florida
- North Miami Beach, Florida
- Port Saint Lucie, Florida
- Sweetwater, Florida
- Tampa, Florida
- East Point, Georgia
And 11 more locations — see the full list below.
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jul 7, 2026 · Source of record for eligibility and locations