RSV InfectionPhase 4NCT07824167
The EMBRACE Study: Enflonsia Monoclonal in Babies - RSV Antibody Concentration Evaluation
A Phase 4 study testing Clesrovimab in people with RSV Infection, run by Emory University at 1 site in United States.
Trial summary
Clesrovimab is an FDA-approved antibody drug recommended for infants younger than 8 months who are entering their first respiratory syncytial virus (RSV) season and whose mothers did not receive an RSV vaccine during pregnancy. It is given to help prevent severe RSV illness. Read more about this study
- Who is it for?
- Ages Up to 8 months
- Conditions the study is for
- RSV Infection
- What is being tested?
- Clesrovimab
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 24 participants
- Where
- 1 siteUnited States
- Study dates
- Sep 2026to Mar 2028
- Phase
- Phase 4
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages Up to 8 months
- All sexes
- No healthy volunteers
- Child
Who may be able to join
- An infant who is <8 months of age at the time of immunization and born during or entering their first respiratory season.
- The infant is in good health as established by medical history and investigator's discretion before entering the study. Chronic medical conditions are acceptable, provided that they are stable.
- Written informed consent is obtained from the participant's parent(s)/legally authorized representative(s) (LAR) prior to performing any study specific procedures, including screening evaluations.
- At least one parent/legally authorized representative of the subject is willing and able to maintain communication with the study site for the duration of the study.
- Subject's parent(s)/legally authorized representative(s) is able to understand and comply with the requirements of the protocol including follow-up and illness visits as judged by the investigator.
- Subject is available to complete the follow-up period, which will be approximately 6 months after receipt of the dose of study drug.
Who cannot join
- Any fever (≥ 100.4°F [≥ 38.0°C], regardless of route) or acute illness within 3 days prior to enrollment.
- Any current or expected receipt of immunosuppressive agents including systemic steroids (except for the use of topical steroids according to the judgment of the investigator).
- Known immunodeficiency, including human immunodeficiency virus (HIV).
- Any known allergy or hypersensitivity to immunoglobulin products.
- Hypersensitivity, anaphylaxis, or seizures within 72 hours after any previous administration of a vaccine.
- Receipt of polyclonal antibodies and/or plasma at any time prior to or planned during the study follow-up period.
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- Receipt of palivizumab, nirsevimab, or other RSV monoclonal antibody or any RSV vaccine at any time prior to or planned during the study.
- Maternal receipt of an RSV vaccine during her pregnancy with the infant participant.
- Use of any investigational product or non-registered product (drug or vaccine) other than the study product during the period starting 30 days before study product administration, or planned use during the study period.
- Concurrent enrollment in another interventional study.
- Any other condition that, in the judgment of the investigator, would be a risk to subject's safety and/or may interfere with study procedures or interpretation of results.
- Unable to obtain baseline blood (minimum 0.5 mL) or nasal sample.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Christina Rostad, MD contact
United States1 site
Emory Children's Center-Vaccine Research Clinic
Atlanta, Georgia, 30322
Jessica McCaffery, PhD, 404-727-4044, ecc.vaccine@emory.edu
Christina Rostad, MD
About this study
Official title: Longitudinal Serum and Mucosal RSV Antibodies Following Clesrovimab (Enflonsia™, Merck) Administration in Infants During Their First Respiratory Season or [The EMBRACE Study: Enflonsia™ Monoclonal in Babies - RSV Antibody Concentration Evaluation]
Clesrovimab is an FDA-approved antibody drug recommended for infants younger than 8 months who are entering their first respiratory syncytial virus (RSV) season and whose mothers did not receive an RSV vaccine during pregnancy. It is given to help prevent severe RSV illness. This study will measure clesrovimab and other RSV antibodies in infants' blood and noses to learn how much of the drug reaches the nose, how long the antibodies remain, and how antibody levels change if an infant becomes infected with RSV.
Read the detailed description
The study will enroll 24 infants younger than 8 months who are entering their first RSV season. The study includes minors and may include newborn infants. Written permission will be obtained from a parent or legally authorized representative before any study procedures occur. Infant assent will not be obtained because the participants are too young to provide it.
Each infant will receive one injection of clesrovimab as part of the usual care recommended to prevent serious RSV illness. Study staff will collect blood and nasal samples before the injection, at either Day 8 or Day 45, and at Day 181 after injection. Parent or legally authorized representative will also complete one safety follow-up visit by phone call at either Day 8 or Day 45.
Each infant will participate for about six months after receiving clesrovimab. Recruitment will invite families of eligible infants through the Emory Children's Center-Vaccine Research Clinic (ECC-VRC), Emory and community outreach, healthcare clinics, electronic health record messages, advertisements, and approved online recruitment methods.
Blood, nasal samples, and study data will be stored for the planned study tests. Remaining samples will be stored without information that directly identifies the infant, such as the infant's name or date of birth (de-identified), until the planned tests are complete and the study is closed. They will not be stored for unrelated future research. Study records will be kept as required by Emory, the study sponsor, and applicable rules.
- Conditions
- RSV Infection
- Being tested
- Clesrovimab
- Keywords
- Clesrovimab
- Medical subject headings
- Respiratory Syncytial Virus Infections
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ClesrovimabBiological
Also called Enflonsia™
Clesrovimab (ENFLONSIA™) is a commercially available product that is administered as part of standard-of-care RSV prevention.
| Study group | Role | What they receive |
|---|---|---|
| Infants Receiving Clesrovimab (Enflonsia™) | Experimental | Participants will receive a single injection of clesrovimab intramuscularly in the anterolateral thigh at a dose of 105 mg, at Visit 1 (Day 1). Receives: Biological: Clesrovimab |
What is being measured
The primary outcome is the main question the study is designed to answer.
Geometric mean concentration (GMC) of serum RSV pre-fusion (preF) binding IgG antibodies
RSV pre-fusion (preF) IgG binding antibodies in serum specimens will be quantified. Assay results will be reported as concentrations (arbitrary units per milliliter, AU/mL) derived from a calibrated standard curve. Serum RSV preF IgG concentrations will be summarized as geometric mean concentrations (GMC) at each study timepoint.
Measured: Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181
Geometric mean concentration (GMC) of nasal RSV pre-fusion (preF) binding IgG antibodies
RSV pre-fusion (preF) IgG binding antibodies in nasal specimens will be quantified. Assay results will be reported as concentrations (arbitrary units per milliliter, AU/mL) derived from a calibrated standard curve.
For nasal specimens, RSV preF IgG concentrations will be normalized to total human IgG concentration. Normalized nasal antibody values will be summarized as GMC.
Measured: Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181
Geometric mean titers (GMT) of serum RSV-A neutralizing antibodies
Serum RSV neutralizing antibody titers will be measured using a microneutralization assay. Neutralizing antibody titers will be reported as reciprocal dilution EC50 titers (the serum dilution resulting in 50% neutralization) and summarized as geometric mean titers (GMTs).
Measured: Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181
Secondary outcomes (2)
Serum Geometric mean concentration (GMC) of clesrovimab
Serum clesrovimab concentrations will be reported in concentration units and summarized as geometric mean concentrations (GMC) at each study timepoint.
Measured: Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181
Urea-normalized GMC of clesrovimab in the nasal mucosa
Clesrovimab concentrations will be normalized to urea concentration for nasal samples to account for variability in epithelial lining fluid dilution. Urea-normalized nasal clesrovimab concentrations will be summarized as GMC.
Measured: Baseline (Day 1), assigned early follow-up timepoint (Day 8 or Day 45) and Day 181
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Sep 2026
- Study startSep 2026 (estimated)
- Primary completionMar 2028 (estimated)
- Study completionMar 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for RSV InfectionStudies of the same condition, open and under way.
- More trials run by Emory UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- This is a Phase 4, open-label, single-center, interventional clinical study designed to characterize immunologic and pharmacokinetic responses following administration of clesrovimab. The study follows a non-randomized design. No control group or comparator treatment is included.
- Masking
- None (open label)
- Enrolment
- 24 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Emory University
- Sponsor type
- University, hospital or other
- Collaborators
- Merck Sharp & Dohme LLC
- Responsible party
- Principal investigator, Christina Rostad, Emory University
- Investigators
- Christina Rostad, MD, Principal investigator, Emory University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07824167
- Sponsor's protocol ID
- 2026P001574
- Status last verified
- Sep 2026
- First submitted
- 11 Sep 2026
- Last updated
- 17 Sep 2026
- Results posted
- No
- Data monitoring committee
- Yes
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- No