Children <24 Months Hospitalized for RSV-related Lower Respiratory Tract InfectionSiRiUSNCT07893652
Severe Pediatric Respiratory Syncytial Virus Infections Occurring in the Era of Antiviral Prophylaxis
An observational study of Children <24 Months Hospitalized for RSV-related Lower Respiratory Tract Infection, run by Assistance Publique - Hôpitaux de Paris at 1 site in France.
Trial summary
Hospitalization for RSV lower respiratory tract infections (LRTI) still occurs, including in infants having received nirsevimab/clesrovimab or born to mothers vaccinated with Abrysvo. Read more about this study
- Who is it for?
- Ages Up to 24 months
- Conditions the study is for
- Children <24 Months Hospitalized for RSV-related Lower Respiratory Tract Infection
- What is being tested?
- Prior exposure to prophylactic treatment with Abrysvo or nirsevimab/clesrovimab and Non-exposure to prior prophylactic treatment
- Type of treatment
- Vaccines
- How many people
- 300 participants
- Where
- 1 siteFrance
- Study dates
- 15 Nov 2026to 15 Dec 2028
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
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 24 months
- All sexes
- No healthy volunteers
- Child
Study population: Pediatric patients hospitalized for RSV LRTI
Who may be able to join
- Child < 24 months
- Admission to the hospital for RSV-related lower respiratory tract infections (LRTI), on the basis of the treating physician's decision and a confirmation of RSV by means of a positive result of a test performed in accordance with routine clinical practice
- Informed consent of legal representative(s) of the child
Who cannot join
- Prior exposure to other RSV prophylaxis than maternal Abrysvo vaccine or nirsevimab/clesrovimab
- Admission not directly related to RSV-related LRTI, according to the investigator's judgment
- Nosocomial RSV-associated LRTI (defined by respiratory symptoms attributed to RSV occurring >7 days after admission for another cause)
- No healthcare insurance
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
France1 site
Hôpital Necker - Enfants Malades
Paris, 75015
Paul BASTARD, MD,PhD, 01 44 49 48 26 ext. +33, paul.bastard@aphp.fr
Aminata TRAORE, Project advisor, 01 42 19 27 34 ext. +33, aminata.traore6@aphp.fr
About this study
Hospitalization for RSV lower respiratory tract infections (LRTI) still occurs, including in infants having received nirsevimab/clesrovimab or born to mothers vaccinated with Abrysvo.
We hypothesize that pediatric patients hospitalized for RSV LRTIs occurring in the era of large use of prophylaxis, could be, at least in part, explained by virological factors (emergence/selection of variants with decreased susceptibility to prophylaxis) and/or immunological factors (inherited immune deficiency, presence of auto-antibodies neutralizing anti-viral cytokines such as type I interferons, impaired mucosal responses or mucosal pharmacokinetics issues inducing low levels of local concentrations of nirsevimab/clesrovimab).
Read the detailed description
In this cohort study, all paediatric patients hospitalized for severe RSV infection will be included at the time of hospitalization.
We aim to detect virological variants with decreased sensitivity to the prophylaxis previously administered (Abrysvo and/or nirsevimab/clesrovimab) will be performed by sequencing the full-length RSV genome to detect any polymorphisms and/or resistance associated mutations in the F protein.
Nasal swabs, salivary and blood samples will be collected at inclusion. Those hospitalized for ≥ 5 days will undergo another nasopharyngeal sample at day 7 +/-2 of hospitalization. Two groups of patients will be identified according to their exposure or non-exposure to prophylaxis.
Briefly:
- with nasopharyngeal swab using amplicon sequencing strategy we will analyze genetic variation in all genomic regions of RSV-A and -B (method using oligonucleotide probes designed to target and capture all RSV genome regions, followed by NGS)
- with plasma aliquot of blood we will measure of RSV-specific antibody (preF) level using an amplicon sequencing strategy previously validated in the French National Reference Center for Respiratory Viruses (Institut Pasteur)
- with saliva swab we will study immune defences against RSV at the level of the mucous membranes, studying the local immune response to RSV and inflammatory markers.
- Being tested
- Prior exposure to prophylactic treatment with Abrysvo or nirsevimab/clesrovimab, Non-exposure to prior prophylactic treatment
- Keywords
- Respiratory Syncytial Virus Infections, Lower respiratory tract infections (LRTI), Hospitalization, Infants
- 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.
Prior exposure to prophylactic treatment with Abrysvo or nirsevimab/clesrovimabBiological
Being born to a woman having received Abrysvo vaccine ≥ 14 days before delivery (thus, children born to mothers vaccinated <14 days before delivery will be considered as "unexposed" to Abrysvo) AND being less than 12 months of age at the time of admission for RSV LRTI OR having received nirsevimab or clesrovimab ≥ 7 days and < 12 months before admission for RSV LRTI (thus, children admitted < 7 days after nirsevimab/clesrovimab administration will be considered as "unexposed" to nirsevimab/clesrovimab).
Non-exposure to prior prophylactic treatmentBiological
all other children will be considered as non-exposed to prophylaxis
| Study group | Role | What they receive |
|---|---|---|
| Exposure or non-exposure to prior prophylactic treatment. | Child < 24 months admitted to the hospital for RSV-related lower respiratory tract infection (LRTI) Receives: Biological: Prior exposure to prophylactic treatment with Abrysvo or nirsevimab/clesrovimab; Biological: Non-exposure to prior prophylactic treatment |
What is being measured
The primary outcome is the main question the study is designed to answer.
RSV variants with reduced sensitivity to prophylaxis
Detection of virological variants with decreased sensitivity to the prophylaxis previously administered (nirsevimab/clesrovimab and/or Abrysvo), performed by sequencing the full-length RSV genome to detect any polymorphisms and/or resistance associated mutations in the F protein
Measured: Day0/At inclusion
Secondary outcomes (4)
RSV variants with reduced sensitivity to nirsevimab/clesrovimab according to age at hospitalization
Detection among children exposed to nirsevimab/clesrovimab before 12 months of age and assessment of RSV harboring polymorphisms or resistance-associated substitutions conferring decreased susceptibility to nirsevimab/clesrovimab in those hospitalized for RSV LRTI during their 1st year of life versus those hospitalized during their 2nd year of life
Measured: Day 0
Immunological characteristics of children hospitalized with RSV LRTI
Detection of the following immunological characteristics:
- identification of a primary immune deficiency (previously undiagnosed in the participants), by whole exome sequencing
- detection of auto-antibodies neutralizing type I IFNs in serum, by a luciferase reporter assay and multiplex detection assays
Measured: Day 0
Mucosal immunity of children hospitalized with RSV LRTI
Assessment of mucosal immunity (detection in saliva swabs of IgG or SIgA anti-RSV response (protein F), and correlation with functional neutralizing anti-RSV responses (RSV A and B strain))
Measured: Day 0
Viral kinetics
Evaluation of the kinetics of RSV RNA in nasal swab at inclusion and day 7+/-2 (for patients still hospitalized), using qPCR
Measured: Day 0 and 7 +/-2 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Oct 2026
- Study start15 Nov 2026 (estimated)
- Primary completion15 Nov 2028 (estimated)
- Study completion15 Dec 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Children <24 Months Hospitalized for RSV-related Lower Respiratory Tract InfectionStudies of the same condition, open and under way.
- More trials run by Assistance Publique - Hôpitaux de ParisThe 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 300 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Assistance Publique - Hôpitaux de Paris
- Sponsor type
- University, hospital or other
- Collaborators
- URC-CIC Paris Descartes Necker Cochin
- Responsible party
- Sponsor
- Investigators
- Paul BASTARD, MD, PhD, Principal investigator, Assistance Publique - Hôpitaux de Paris (AP-HP)Pierre FRANGE, MD, PhD, Study director, Assistance Publique - Hôpitaux de Paris (AP-HP)
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07893652
- Sponsor's protocol ID
- APHP251263
- Other IDs
- ID-RCB Number
- Acronym
- SiRiUS
- Status last verified
- Oct 2026
- First submitted
- 19 Oct 2026
- Last updated
- 26 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 26 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Severe Pediatric Respiratory Syncytial Virus Infections Occurring in the Era of Antiviral Prophylaxis
- ClinicalTrials.gov ID
- NCT07893652
- Acronym / sponsor ID
- SiRiUS / APHP251263
- Keywords
- Respiratory Syncytial Virus Infections, Lower respiratory tract infections (LRTI), Hospitalization, Infants
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 300 participants (estimated)
- Lead sponsor
- Assistance Publique - Hôpitaux de ParisUniversity, hospital or other
- Collaborators
- URC-CIC Paris Descartes Necker Cochin
- Study start
- 15 Nov 2026 (estimated)
- Primary completion
- 15 Nov 2028 (estimated)
- Study completion
- 15 Dec 2028 (estimated)
- First posted
- 26 Oct 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Hospitalization for RSV lower respiratory tract infections (LRTI) still occurs, including in infants having received nirsevimab/clesrovimab or born to mothers vaccinated with Abrysvo.
We hypothesize that pediatric patients hospitalized for RSV LRTIs occurring in the era of large use of prophylaxis, could be, at least in part, explained by virological factors (emergence/selection of variants with decreased susceptibility to prophylaxis) and/or immunological factors (inherited immune deficiency, presence of auto-antibodies neutralizing anti-viral cytokines such as type I interferons, impaired mucosal responses or mucosal pharmacokinetics issues inducing low levels of local concentrations of nirsevimab/clesrovimab).
Detailed description
In this cohort study, all paediatric patients hospitalized for severe RSV infection will be included at the time of hospitalization.
We aim to detect virological variants with decreased sensitivity to the prophylaxis previously administered (Abrysvo and/or nirsevimab/clesrovimab) will be performed by sequencing the full-length RSV genome to detect any polymorphisms and/or resistance associated mutations in the F protein.
Nasal swabs, salivary and blood samples will be collected at inclusion. Those hospitalized for ≥ 5 days will undergo another nasopharyngeal sample at day 7 +/-2 of hospitalization. Two groups of patients will be identified according to their exposure or non-exposure to prophylaxis.
Briefly:
- with nasopharyngeal swab using amplicon sequencing strategy we will analyze genetic variation in all genomic regions of RSV-A and -B (method using oligonucleotide probes designed to target and capture all RSV genome regions, followed by NGS)
- with plasma aliquot of blood we will measure of RSV-specific antibody (preF) level using an amplicon sequencing strategy previously validated in the French National Reference Center for Respiratory Viruses (Institut Pasteur)
- with saliva swab we will study immune defences against RSV at the level of the mucous membranes, studying the local immune response to RSV and inflammatory markers.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Exposure or non-exposure to prior prophylactic treatment. | – | Biological: Prior exposure to prophylactic treatment with Abrysvo or nirsevimab/clesrovimab, Biological: Non-exposure to prior prophylactic treatmentChild < 24 months admitted to the hospital for RSV-related lower respiratory tract infection (LRTI) |
Who may qualify
- Ages
- Up to 24 months
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child
- Study population
- Pediatric patients hospitalized for RSV LRTI
Key inclusion criteria (3 listed)
- Child < 24 months
- Admission to the hospital for RSV-related lower respiratory tract infections (LRTI), on the basis of the treating physician's decision and a confirmation of RSV by means of a positive result of a test performed in accordance with routine clinical practice
- Informed consent of legal representative(s) of the child
Key exclusion criteria (4 listed)
- Prior exposure to other RSV prophylaxis than maternal Abrysvo vaccine or nirsevimab/clesrovimab
- Admission not directly related to RSV-related LRTI, according to the investigator's judgment
- Nosocomial RSV-associated LRTI (defined by respiratory symptoms attributed to RSV occurring >7 days after admission for another cause)
- No healthcare insurance
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Prior exposure to prophylactic treatment with Abrysvo or nirsevimab/clesrovimabBeing born to a woman having received Abrysvo vaccine ≥ 14 days before delivery (thus, children born to mothers vaccinated <14 days before delivery will be considered as "unexposed" to Abrysvo) AND being less than 12 months of age at the time of admission for RSV LRTI OR having received nirsevimab or clesrovimab ≥ 7 days and < 12 months before admission for RSV LRTI (thus, children admitted < 7 days after nirsevimab/clesrovimab administration will be considered as "unexposed" to nirsevimab/clesrovimab). | Biological | Exposure or non-exposure to prior prophylactic treatment. |
| Non-exposure to prior prophylactic treatmentall other children will be considered as non-exposed to prophylaxis | Biological | Exposure or non-exposure to prior prophylactic treatment. |
Primary outcome
RSV variants with reduced sensitivity to prophylaxis
Time frame: Day0/At inclusion
Detection of virological variants with decreased sensitivity to the prophylaxis previously administered (nirsevimab/clesrovimab and/or Abrysvo), performed by sequencing the full-length RSV genome to detect any polymorphisms and/or resistance associated mutations in the F protein
4 secondary outcomes
RSV variants with reduced sensitivity to nirsevimab/clesrovimab according to age at hospitalization
Time frame: Day 0
Immunological characteristics of children hospitalized with RSV LRTI
Time frame: Day 0
Mucosal immunity of children hospitalized with RSV LRTI
Time frame: Day 0
Viral kinetics
Time frame: Day 0 and 7 +/-2 days
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 Oct 2026.
- Individual participant dataSharing planned: No
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Paul BASTARD, MD, PhD principal investigator
Assistance Publique - Hôpitaux de Paris (AP-HP)
Pierre FRANGE, MD, PhD study director
Assistance Publique - Hôpitaux de Paris (AP-HP)
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Children <24 Months Hospitalized for RSV-related Lower Respiratory Tract Infection, run by Assistance Publique - Hôpitaux de Paris at 1 site in France.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 26 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in France. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Paul BASTARD, MD,PhD (01 44 49 48 26 ext. +33, paul.bastard@aphp.fr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
RSV variants with reduced sensitivity to prophylaxis (time frame: Day0/At inclusion). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Oct 2026.