Respiratory Syncytial VirusBEARNCT06325332
BEYFORTUS™ (Nirsevimab) Effectiveness Against Medically-Attended RSV Events in Infants (BEAR Study)
An observational study of Respiratory Syncytial Virus, run by Sanofi Pasteur, a Sanofi Company at 1 site in United States.
Trial summary
The primary objectives of the study are: To estimate the effectiveness of nirsevimab against polymerase chain reaction (PCR)-confirmed RSV (1) lower respiratory tract (LRTD) and (2) related medical encounters. the secondary objectives are: 1. Read more about this study
- Who is it for?
- Ages 0 days to 12 monthsHealthy volunteers can take part
- Conditions the study is for
- Respiratory Syncytial Virus
- What is being tested?
- Nirsevimab
- Type of treatment
- Injection or infusion
- How many people
- 49,680 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Apr 2024to 30 Jun 2025
- Phase
- Observational
- Are there results?
- None posted in the registry
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 0 days to 12 months
- All sexes
- Healthy volunteers accepted
- Child
Study population: The study is an observational, retrospective cohort study designed to evaluate the effectiveness of nirsevimab to prevent RSV-confirmed respiratory-related medical encounters and health care utilization in infants entering their first RSV season compared to no treatment in the United States. The source population is infants ≥ 37 weeks gestational age and aged 0 to 12 months (calendar age) entering their first RSV season and without significant medical history. There is also a high-risk infant population with infants < 37 WGA and aged 0 to 12 months (calendar age), entering their first RSV season and infants ≥ 37 weeks with significant medical history diagnosed at birth up to the end of the observation period (ie, 30 April 2024). The study will aim to enroll approximately 33,000 infants.
Who may be able to join
- The Kaiser Permanente Northern California, USA (KPNC) member born on or after 01 April 2023 for Cohort 1 and Cohort 2.
- Eligible to receive nirsevimab as defined by the product indication.
- KPNC infants entering their first RSV season.
Who cannot join
- Mother was administered an RSV vaccine during her pregnancy with the infant participant.
- Mother of infant participant was not a KPNC member during pregnancy.
- Mother did not deliver the infant participant at a KPNC facility.
- Infant receipt of other RSV pre-exposure prophylaxis (ie, Palivizumab).
- Note: The above information is not intended to contain all considerations relevant to a potential participation in a clinical trial.
Trial locations and contacts
1 site in 1 country.
United States1 site
Kaiser Permanente Northern California: Site number 0001
Oakland, California, 94612
About this study
The primary objectives of the study are: To estimate the effectiveness of nirsevimab against polymerase chain reaction (PCR)-confirmed RSV (1) lower respiratory tract (LRTD) and (2) related medical encounters.
the secondary objectives are:
- To estimate the effectiveness of nirsevimab against medical encounters with a respiratory related diagnosis.
- To estimate the effectiveness of nirsevimab against medical encounters with an LRTD diagnosis.
- To estimate the impact of nirsevimab on PCR-confirmed RSV.
- To estimate the impact of nirsevimab on medical encounters with an otitis media diagnosis.
- To estimate the impact of nirsevimab on antibiotic prescription.
- Conditions
- Respiratory Syncytial Virus
- Being tested
- Nirsevimab
- Keywords
- RSV
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
NirsevimabOther
Also called Beyfortus™
Route of Administration: Intramuscular Pharmaceutical Form: Solution for injection
| Study group | Role | What they receive |
|---|---|---|
| Cohort 1: Nirsevimab-Exposed Cohort | Full-term (born ≥ 37 weeks gestational age) infants born on or after 01 April 2023, without a high-risk condition, who receive nirsevimab before or during their first RSV season per recommendations, ie, before or during the 2023-2024 RSV season. Receives: Other: Nirsevimab | |
| Cohort 2: Comparator Cohort | Full-term (born ≥ 37 weeks gestational age) infants born on or after 01 April 2023, without a high-risk condition, who do not receive nirsevimab before or during the 2023-2024 RSV season. | |
| Cohort 3: Historical Control Cohort | Full-term (born ≥ 37 weeks gestational age) infants without a high-risk condition from previous RSV seasons 2016-2017, 2017-2018, 2018-2019, 2019-2020, and 2022-2023. The 2020-2021 and 2021-2022 seasons are excluded due to low circulation of RSV during the COVID-19 pandemic. Historical seasons' data are intended for descriptive purpose only, to contextualize the impact of the treatment during the 2023-2024 season. | |
| Cohort 4: Infant Cohort with High-Risk Conditions | Infants born < 37 weeks gestational age and those diagnosed with a high-risk condition between birth and the end of the observation period (regardless of gestational age at birth), will be considered infants with high-risk conditions. Infants with high-risk conditions will be excluded from Cohort 1, Cohort 2, and Cohort 3. Descriptive statistics will be separately assessed for this high-risk cohort. |
What is being measured
The primary outcome is the main question the study is designed to answer.
Incidence of first episodes of polymerase chain reaction (PCR)-confirmed RSV with an lower respiratory tract disease (LRTD)
Incidence of first episodes of polymerase chain reaction (PCR)-confirmed RSV with an lower respiratory tract disease (LRTD) diagnosis identified using International Classification of Diseases, Tenth Revision (ICD)
Measured: Approximately 6 months
Number of medical encounters associated with the first episode of PCR-confirmed RSV with a LRTD diagnosis
Number of medical encounters associated with the first episode of PCR-confirmed RSV with a LRTD diagnosis identified using ICD-10 codes: outpatient (OP) visits, emergency department (ED) visits, inpatient (IP) hospitalizations or intensive care unit (ICU) hospitalizations.
Measured: Approximately 6 months
Secondary outcomes (5)
Number of respiratory-related medical encounters
Number of respiratory-related medical encounters (ie, Outpatient visits, Emergency department visits, In patient hospitalizations, and Intensive care unit hospitalizations) by ICD-10 codes.
Measured: Approximately 6 months
Number of respiratory-related medical encounters for LRTD by ICD-10 codes
Number of respiratory-related medical encounters for LRTD by ICD-10 codes.
Measured: Approximately 6 months
Incidence of PCR-confirmed RSV (first occurrence of season)
Incidence of PCR-confirmed RSV (first occurrence of season).
Measured: Approximately 6 months
Number of medical encounters for otitis media by ICD-10 codes
Number of medical encounters for otitis media by ICD-10 codes.
Measured: Approximately 6 months
Number of antibiotic prescriptions by National Drug Code (NDC) codes
Number of antibiotic prescriptions by NDC codes.
Measured: Approximately 6 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Mar 2024
- Study start1 Apr 2024
- Primary completion30 Jun 2025
- Study completion30 Jun 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Respiratory Syncytial VirusStudies of the same condition, open and under way.
- More trials run by Sanofi Pasteur, a Sanofi CompanyThe 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
- Retrospective
- Enrolment
- 49,680 participants (actual)
Sponsor and investigators
- Lead sponsor
- Sanofi Pasteur, a Sanofi Company
- Sponsor type
- Industry (pharma, biotech, devices)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06325332
- Sponsor's protocol ID
- RSV00080
- Acronym
- BEAR
- Status last verified
- Nov 2025
- First submitted
- 15 Mar 2024
- Last updated
- 5 Nov 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
- Individual data sharing
- Yes: Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org
Study at a glance
From the registry record, last updated by the sponsor on 5 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- BEYFORTUS™ (Nirsevimab) Effectiveness Against Medically-Attended RSV Events in Infants (BEAR Study)
- ClinicalTrials.gov ID
- NCT06325332
- Acronym / sponsor ID
- BEAR / RSV00080
- Conditions
- Respiratory Syncytial Virus
- Keywords
- RSV
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 49,680 participants (actual)
- Lead sponsor
- Sanofi Pasteur, a Sanofi CompanyIndustry (pharma, biotech, devices)
- Study start
- 1 Apr 2024 (actual)
- Primary completion
- 30 Jun 2025 (actual)
- Study completion
- 30 Jun 2025 (actual)
- First posted
- 22 Mar 2024 (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.
The primary objectives of the study are: To estimate the effectiveness of nirsevimab against polymerase chain reaction (PCR)-confirmed RSV (1) lower respiratory tract (LRTD) and (2) related medical encounters.
the secondary objectives are:
- To estimate the effectiveness of nirsevimab against medical encounters with a respiratory related diagnosis.
- To estimate the effectiveness of nirsevimab against medical encounters with an LRTD diagnosis.
- To estimate the impact of nirsevimab on PCR-confirmed RSV.
- To estimate the impact of nirsevimab on medical encounters with an otitis media diagnosis.
- To estimate the impact of nirsevimab on antibiotic prescription.
Study design
- Observational model
- Cohort
- Time perspective
- Retrospective
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Cohort 1: Nirsevimab-Exposed Cohort | – | Other: NirsevimabFull-term (born ≥ 37 weeks gestational age) infants born on or after 01 April 2023, without a high-risk condition, who receive nirsevimab before or during their first RSV season per recommendations, ie, before or during the 2023-2024 RSV season. |
| Cohort 2: Comparator Cohort | – | –Full-term (born ≥ 37 weeks gestational age) infants born on or after 01 April 2023, without a high-risk condition, who do not receive nirsevimab before or during the 2023-2024 RSV season. |
| Cohort 3: Historical Control Cohort | – | –Full-term (born ≥ 37 weeks gestational age) infants without a high-risk condition from previous RSV seasons 2016-2017, 2017-2018, 2018-2019, 2019-2020, and 2022-2023. The 2020-2021 and 2021-2022 seasons are excluded due to low circulation of RSV during the COVID-19 pandemic. Historical seasons' data are intended for descriptive purpose only, to contextualize the impact of the treatment during the 2023-2024 season. |
| Cohort 4: Infant Cohort with High-Risk Conditions | – | –Infants born < 37 weeks gestational age and those diagnosed with a high-risk condition between birth and the end of the observation period (regardless of gestational age at birth), will be considered infants with high-risk conditions. Infants with high-risk conditions will be excluded from Cohort 1, Cohort 2, and Cohort 3. Descriptive statistics will be separately assessed for this high-risk cohort. |
Who may qualify
- Ages
- 0 days to 12 months
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child
- Study population
- The study is an observational, retrospective cohort study designed to evaluate the effectiveness of nirsevimab to prevent RSV-confirmed respiratory-related medical encounters and health care utilization in infants entering their first RSV season compared to no treatment in the United States. The source population is infants ≥ 37 weeks gestational age and aged 0 to 12 months (calendar age) entering their first RSV season and without significant medical history. There is also a high-risk infant population with infants < 37 WGA and aged 0 to 12 months (calendar age), entering their first RSV season and infants ≥ 37 weeks with significant medical history diagnosed at birth up to the end of the observation period (ie, 30 April 2024). The study will aim to enroll approximately 33,000 infants.
Key inclusion criteria (3 listed)
- The Kaiser Permanente Northern California, USA (KPNC) member born on or after 01 April 2023 for Cohort 1 and Cohort 2.
- Eligible to receive nirsevimab as defined by the product indication.
- KPNC infants entering their first RSV season.
Key exclusion criteria (5 listed)
- Mother was administered an RSV vaccine during her pregnancy with the infant participant.
- Mother of infant participant was not a KPNC member during pregnancy.
- Mother did not deliver the infant participant at a KPNC facility.
- Infant receipt of other RSV pre-exposure prophylaxis (ie, Palivizumab).
- Note: The above information is not intended to contain all considerations relevant to a potential participation in a clinical trial.
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 |
|---|---|---|
| NirsevimabAlso: Beyfortus™Route of Administration: Intramuscular Pharmaceutical Form: Solution for injection | Other | Cohort 1: Nirsevimab-Exposed Cohort |
Primary outcome
Incidence of first episodes of polymerase chain reaction (PCR)-confirmed RSV with an lower respiratory tract disease (LRTD)
Time frame: Approximately 6 months
Incidence of first episodes of polymerase chain reaction (PCR)-confirmed RSV with an lower respiratory tract disease (LRTD) diagnosis identified using International Classification of Diseases, Tenth Revision (ICD)
Number of medical encounters associated with the first episode of PCR-confirmed RSV with a LRTD diagnosis
Time frame: Approximately 6 months
Number of medical encounters associated with the first episode of PCR-confirmed RSV with a LRTD diagnosis identified using ICD-10 codes: outpatient (OP) visits, emergency department (ED) visits, inpatient (IP) hospitalizations or intensive care unit (ICU) hospitalizations.
5 secondary outcomes
Number of respiratory-related medical encounters
Time frame: Approximately 6 months
Number of respiratory-related medical encounters for LRTD by ICD-10 codes
Time frame: Approximately 6 months
Incidence of PCR-confirmed RSV (first occurrence of season)
Time frame: Approximately 6 months
Number of medical encounters for otitis media by ICD-10 codes
Time frame: Approximately 6 months
Number of antibiotic prescriptions by National Drug Code (NDC) codes
Time frame: Approximately 6 months
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 5 Nov 2025.
- Individual participant dataSharing planned: Yes. Qualified researchers may request access to patient level data and related study documents including the clinical study report, study protocol with any amendments, blank case report form, statistical analysis plan, and dataset specifications. Patient level data will be anonymized and study documents will be redacted to protect the privacy of trial participants. Further details on Sanofi's data sharing criteria, eligible studies, and process for requesting access can be found at: https://vivli.org
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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. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
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 Respiratory Syncytial Virus, run by Sanofi Pasteur, a Sanofi Company at 1 site in United States.
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 5 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: finished, as of the sponsor's last update on 5 Nov 2025. 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 United States. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Incidence of first episodes of polymerase chain reaction (PCR)-confirmed RSV with an lower respiratory tract disease (LRTD) (time frame: Approximately 6 months). The study lists 2 primary outcomes in all. 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 5 Nov 2025.