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    Clinical Trial Results:
    A Phase 3, Randomized, Double-blind, Placebo-controlled Study to Evaluate the Safety and Efficacy of Nirsevimab, a Monoclonal Antibody With Extended Half-life Against Respiratory Syncytial Virus, in Healthy Preterm and Term Infants in China

    Summary
    EudraCT number
    2021-005075-38
    Trial protocol
    Outside EU/EEA  
    Global end of trial date
    24 Nov 2025

    Results information
    Results version number
    v1(current)
    This version publication date
    07 Jun 2026
    First version publication date
    07 Jun 2026
    Other versions

    Trial information

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    Trial identification
    Sponsor protocol code
    D5290C00006
    Additional study identifiers
    ISRCTN number
    -
    US NCT number
    NCT05110261
    WHO universal trial number (UTN)
    -
    Sponsors
    Sponsor organisation name
    AstraZeneca AB
    Sponsor organisation address
    Forskargatan 18, Södertälje, Sweden, 151 85
    Public contact
    Global Clinical Lead, AstraZeneca AB, +1 877-240-9479, information.center@astrazeneca.com
    Scientific contact
    Global Clinical Lead, AstraZeneca AB, +1 877-240-9479, information.center@astrazeneca.com
    Paediatric regulatory details
    Is trial part of an agreed paediatric investigation plan (PIP)
    No
    Does article 45 of REGULATION (EC) No 1901/2006 apply to this trial?
    No
    Does article 46 of REGULATION (EC) No 1901/2006 apply to this trial?
    No
    Results analysis stage
    Analysis stage
    Final
    Date of interim/final analysis
    19 Dec 2025
    Is this the analysis of the primary completion data?
    No
    Global end of trial reached?
    Yes
    Global end of trial date
    24 Nov 2025
    Was the trial ended prematurely?
    No
    General information about the trial
    Main objective of the trial
    To assess the efficacy of nirsevimab in reducing medically attended lower respiratory tract infection (LRTI) due to reverse transcriptase-polymerase chain reaction (RT-PCR)-confirmed respiratory syncytial virus (RSV), compared to placebo, when administered as a single fixed intramuscular (IM) dose to healthy preterm and term infants born >=29 weeks 0 days gestational age (GA) and entering their first RSV season.
    Protection of trial subjects
    This study was performed in accordance with the relevant International Council for Harmonisation (ICH) Good Clinical Practice Guidelines - which are based on the ethical principles originating from the Declaration of Helsinki and applicable laws and regulations.
    Background therapy
    -
    Evidence for comparator
    -
    Actual start date of recruitment
    24 Nov 2021
    Long term follow-up planned
    No
    Independent data monitoring committee (IDMC) involvement?
    Yes
    Population of trial subjects
    Number of subjects enrolled per country
    Country: Number of subjects enrolled
    China: 800
    Worldwide total number of subjects
    800
    EEA total number of subjects
    0
    Number of subjects enrolled per age group
    In utero
    0
    Preterm newborn - gestational age < 37 wk
    44
    Newborns (0-27 days)
    99
    Infants and toddlers (28 days-23 months)
    657
    Children (2-11 years)
    0
    Adolescents (12-17 years)
    0
    Adults (18-64 years)
    0
    From 65 to 84 years
    0
    85 years and over
    0

    Subject disposition

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    Recruitment
    Recruitment details
    This Phase 3, randomized, double-blind, placebo-controlled study was conducted at 31 investigational sites in healthy pre-term and term infants born >=29 weeks 0 days GA entering their first RSV season.

    Pre-assignment
    Screening details
    This study consisted of a screening period (30 days), treatment period (1 day) and a follow-up period (360 days). A total of 800 participants were randomized in a 2:1 ratio to receive either nirsevimab or placebo. As pre-specified in the statistical analysis plan (SAP), results are presented by treatment group.

    Period 1
    Period 1 title
    Overall Study (overall period)
    Is this the baseline period?
    Yes
    Allocation method
    Randomised - controlled
    Blinding used
    Double blind
    Roles blinded
    Subject, Investigator, Monitor, Carer, Assessor

    Arms
    Are arms mutually exclusive
    Yes

    Arm title
    Nirsevimab
    Arm description
    Participants were randomized to receive a single IM dose of nirsevimab 50 milligram (mg) (if weight <5 kilogram [kg] at time of dosing) or 100 mg (if weight >=5 kg at time of dosing) on Day 1.
    Arm type
    Experimental

    Investigational medicinal product name
    Nirsevimab
    Investigational medicinal product code
    MEDI8897
    Other name
    Pharmaceutical forms
    Solution for injection
    Routes of administration
    Intramuscular use
    Dosage and administration details
    Nirsevimab was administered at a dose of 50 mg (if weight <5 kg at time of dosing) or 100 mg (if weight >=5 kg at time of dosing) on Day 1.

    Arm title
    Placebo
    Arm description
    Participants were randomized to receive a single IM dose of placebo matched to nirsevimab (0.9% weight/volume [w/v] saline) on Day 1.
    Arm type
    Placebo

    Investigational medicinal product name
    Placebo
    Investigational medicinal product code
    Other name
    Pharmaceutical forms
    Solution for injection
    Routes of administration
    Intramuscular use
    Dosage and administration details
    Placebo matched to nirsevimab was administered as 0.9% (w/v) saline (sterile for human use) on Day 1.

    Number of subjects in period 1
    Nirsevimab Placebo
    Started
    532
    268
    Randomized and dosed
    521
    266
    Completed
    512
    261
    Not completed
    20
    7
         Withdrawal by Parent/Guardian
    18
    7
         Unspecified
    1
    -
         Lost to follow-up
    1
    -

    Baseline characteristics

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    Baseline characteristics reporting groups
    Reporting group title
    Nirsevimab
    Reporting group description
    Participants were randomized to receive a single IM dose of nirsevimab 50 milligram (mg) (if weight <5 kilogram [kg] at time of dosing) or 100 mg (if weight >=5 kg at time of dosing) on Day 1.

    Reporting group title
    Placebo
    Reporting group description
    Participants were randomized to receive a single IM dose of placebo matched to nirsevimab (0.9% weight/volume [w/v] saline) on Day 1.

    Reporting group values
    Nirsevimab Placebo Total
    Number of subjects
    532 268 800
    Age Categorical
    Units: Participants
        <=3 months
    300 150 450
        >3 to <=6 months
    195 100 295
        >6 months
    37 18 55
    Age Continuous
    Units: months
        arithmetic mean (standard deviation)
    2.83 ( 1.905 ) 2.83 ( 1.858 ) -
    Gender Categorical
    Units: Participants
        Female
    269 134 403
        Male
    263 134 397
    Race
    Units: Subjects
        Asian
    532 268 800
    Ethnicity
    Units: Subjects
        Not Hispanic or Latino
    532 268 800

    End points

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    End points reporting groups
    Reporting group title
    Nirsevimab
    Reporting group description
    Participants were randomized to receive a single IM dose of nirsevimab 50 milligram (mg) (if weight <5 kilogram [kg] at time of dosing) or 100 mg (if weight >=5 kg at time of dosing) on Day 1.

    Reporting group title
    Placebo
    Reporting group description
    Participants were randomized to receive a single IM dose of placebo matched to nirsevimab (0.9% weight/volume [w/v] saline) on Day 1.

    Subject analysis set title
    Nirsevimab 50 mg
    Subject analysis set type
    Per protocol
    Subject analysis set description
    Participants with weight <5 kg at time of dosing received a single IM dose of nirsevimab 50 mg on Day 1.

    Subject analysis set title
    Nirsevimab 100 mg
    Subject analysis set type
    Per protocol
    Subject analysis set description
    Participants with weight >=5 kg at time of dosing received a single IM dose of nirsevimab 100 mg on Day 1.

    Primary: Number of Participants With all Medically Attended (MA) Lower Respiratory Tract Infection (Inpatient and Outpatient) due to Reverse Transcriptase-Polymerase Chain Reaction-Confirmed Respiratory Syncytial Virus Through 150 Days After Dosing

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    End point title
    Number of Participants With all Medically Attended (MA) Lower Respiratory Tract Infection (Inpatient and Outpatient) due to Reverse Transcriptase-Polymerase Chain Reaction-Confirmed Respiratory Syncytial Virus Through 150 Days After Dosing
    End point description
    The determination of all MA RSV LRTI through 150 days post-dose (during a typical 5-month RSV season) was based on the clinical assessment of LRTI by the Investigator and RSV test results obtained from analyzing the respiratory secretions using a validated RSV RT-PCR assay for the detection of RSV performed in a central laboratory. The LRTI events may occur in the inpatient or outpatient visit setting. Intent-to-treat (ITT) population included all randomized participants.
    End point type
    Primary
    End point timeframe
    From dosing (Day 1) to Day 150
    End point values
    Nirsevimab Placebo
    Number of subjects analysed
    532
    268
    Units: participants
    9
    12
    Statistical analysis title
    Nirsevimab Versus Placebo
    Statistical analysis description
    Relative risk reduction of nirsevimab versus placebo, the 95% confidence interval and p-value were estimated based on Poisson regression with robust variance (including stratification factor [age at randomization and GA group] as covariates) obtained from PROC MIANALYZE after missing data imputation.
    Comparison groups
    Nirsevimab v Placebo
    Number of subjects included in analysis
    800
    Analysis specification
    Pre-specified
    Analysis type
    superiority
    P-value
    = 0.036
    Method
    Poisson regression with robust variance
    Parameter type
    Relative risk reduction, %
    Point estimate
    59.8
    Confidence interval
         level
    95%
         sides
    2-sided
         lower limit
    5.8
         upper limit
    82.9

    Secondary: Number of Participants With Medically Attended Lower Respiratory Tract Infection (Protocol-Defined, Inpatient and Outpatient) due to Reverse Transcriptase-Polymerase Chain Reaction-Confirmed Respiratory Syncytial Virus Through 150 Days After Dosing

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    End point title
    Number of Participants With Medically Attended Lower Respiratory Tract Infection (Protocol-Defined, Inpatient and Outpatient) due to Reverse Transcriptase-Polymerase Chain Reaction-Confirmed Respiratory Syncytial Virus Through 150 Days After Dosing
    End point description
    Determination of MA RSV LRTI through 150 days post-dose (i.e., typical 5-month RSV season) was based on assessment by Investigator according to protocol definition; RSV test results from analyzing respiratory secretions using validated RSV RT-PCR for detecting RSV in inpatient/outpatient visit. ITT population included all randomized participants.
    End point type
    Secondary
    End point timeframe
    From dosing (Day 1) to Day 150
    End point values
    Nirsevimab Placebo
    Number of subjects analysed
    532
    268
    Units: participants
    1
    3
    No statistical analyses for this end point

    Secondary: Number of Participants With Hospitalizations due to Reverse Transcriptase-Polymerase Chain Reaction-Confirmed Respiratory Syncytial Virus Lower Respiratory Tract Infection (Protocol-Defined) Through 150 Days After Dosing

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    End point title
    Number of Participants With Hospitalizations due to Reverse Transcriptase-Polymerase Chain Reaction-Confirmed Respiratory Syncytial Virus Lower Respiratory Tract Infection (Protocol-Defined) Through 150 Days After Dosing
    End point description
    RSV hospitalization: respiratory hospitalization with positive RSV test within approximately 2 days of hospital admission (primary) or new onset of respiratory symptoms in already hospitalized participant with objective measure of worsening respiratory status and positive RSV test (nosocomial). ITT population included all randomized participants.
    End point type
    Secondary
    End point timeframe
    From dosing (Day 1) to Day 150
    End point values
    Nirsevimab Placebo
    Number of subjects analysed
    532
    268
    Units: participants
    1
    2
    No statistical analyses for this end point

    Secondary: Number of Participants With Treatment-Emergent Adverse Events (TEAEs), Treatment-Emergent Serious Adverse Events (TESAEs), Treatment-Emergent Adverse Events of Special Interest (TEAESIs), and New Onset Chronic Disease (NOCDs)

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    End point title
    Number of Participants With Treatment-Emergent Adverse Events (TEAEs), Treatment-Emergent Serious Adverse Events (TESAEs), Treatment-Emergent Adverse Events of Special Interest (TEAESIs), and New Onset Chronic Disease (NOCDs)
    End point description
    AE:any untoward medical occurrence in participant/clinical study participant administered study drug and did not necessarily have causal relationship with study drug. SAE:AE that resulted in death, was immediately life-threatening, required inpatient hospitalization/prolongation of existing hospitalization,resulted in persistent or significant disability/incapacity, was congenital anomaly or birth defect or important medical event that jeopardized participant or required medical treatment. TEAE:AE that occurred on and after administration of study drug through Day 361. AESI:1 of scientific and medical interest specific to understanding of study drug and required close monitoring and rapid communication by Investigator to Sponsor. NOCD:newly diagnosed medical condition of chronic, ongoing nature, observed after receiving study drug and assessed by Investigator as medically significant. As-treated population:all randomized participants who received any amount of study drug.
    End point type
    Secondary
    End point timeframe
    From first dose of study drug (Day 1) up to end of follow-up period (Day 361)
    End point values
    Nirsevimab Placebo
    Number of subjects analysed
    521
    266
    Units: participants
        TEAEs
    473
    247
        TESAEs
    63
    47
        TEAESIs
    1
    0
        NOCDs
    0
    0
    No statistical analyses for this end point

    Secondary: Serum Concentrations of Nirsevimab

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    End point title
    Serum Concentrations of Nirsevimab
    End point description
    Blood samples were collected at specified timepoints to determine the serum concentrations of nirsevimab. The pharmacokinetics (PK) population included all participants who had received any dose of study drug and had at least 1 measurable post-dose serum PK observation and for whom PK blood samples were assumed not to be affected by factors such as important protocol deviations (to be determined prior to unblinding). As pre-specified in the SAP, serum concentrations are presented by weight on study Day 1 (weight <5 kg or >=5 kg). During the study, participants missed few scheduled site visits for sample collection, and only participants with data collected at specific timepoints are reported. Here, n= number of participants with data collected at the specified timepoints.
    End point type
    Secondary
    End point timeframe
    Days 15, 151 and 361
    End point values
    Nirsevimab 50 mg Nirsevimab 100 mg
    Number of subjects analysed
    160
    311
    Units: microgram per milliliter
    arithmetic mean (standard deviation)
        Day 15 (n=160, 309)
    95.232 ( 22.362 )
    141.240 ( 25.904 )
        Day 151 (n=149, 311)
    22.802 ( 5.435 )
    38.395 ( 10.707 )
        Day 361 (n=140, 292)
    2.886 ( 1.210 )
    5.117 ( 2.242 )
    No statistical analyses for this end point

    Secondary: Number of Participants With Anti-Drug Antibody (ADA) Against Nirsevimab

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    End point title
    Number of Participants With Anti-Drug Antibody (ADA) Against Nirsevimab
    End point description
    Blood samples were collected for assessment of ADA against nirsevimab. Treatment-emergent ADA positive was defined as either treatment-induced ADA positive (ADA negative at baseline and post-baseline ADA positive) or treatment-boosted ADA positive (ADA positive at baseline and boosted the pre-existing titre that was boosted to a 4-fold or higher level following study drug administration). Number of participants with treatment-emergent ADA positive sample is presented. As-treated population included all randomized participants who received any amount of study drug. Only participants with data collected are reported
    End point type
    Secondary
    End point timeframe
    From first dose of study drug (Day 1) up to Day 361
    End point values
    Nirsevimab Placebo
    Number of subjects analysed
    491
    254
    Units: participants
    48
    17
    No statistical analyses for this end point

    Adverse events

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    Adverse events information
    Timeframe for reporting adverse events
    Adverse events and deaths were collected from first dose of study drug (Day 1) up to end of follow-up period (Day 361)
    Adverse event reporting additional description
    As-treated population included all randomized participants who received any amount of study drug. As pre-specified in SAP, results are presented by treatment group.
    Assessment type
    Systematic
    Dictionary used for adverse event reporting
    Dictionary name
    MedDRA
    Dictionary version
    28.0
    Reporting groups
    Reporting group title
    Placebo
    Reporting group description
    Participants were randomized to receive a single IM dose of placebo matched to nirsevimab (0.9% [w/v] saline) on Day 1.

    Reporting group title
    Nirsevimab
    Reporting group description
    Participants were randomized to receive a single IM dose of nirsevimab 50 mg (if weight <5 kg at time of dosing) or 100 mg (if weight >=5 kg at time of dosing) on Day 1.

    Serious adverse events
    Placebo Nirsevimab
    Total subjects affected by serious adverse events
         subjects affected / exposed
    47 / 266 (17.67%)
    63 / 521 (12.09%)
         number of deaths (all causes)
    0
    0
         number of deaths resulting from adverse events
    0
    0
    Neoplasms benign, malignant and unspecified (incl cysts and polyps)
    Haemangioma
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Haemangioma of skin
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Nasal neoplasm benign
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Testicular yolk sac tumour
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Vascular disorders
    Scalp haematoma
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Kawasaki's disease
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pregnancy, puerperium and perinatal conditions
    Jaundice neonatal
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Reproductive system and breast disorders
    Acquired hydrocele
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Injury, poisoning and procedural complications
    Foreign body in respiratory tract
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Head injury
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Congenital, familial and genetic disorders
    Cerebral palsy
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Congenital arterial malformation
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Cryptorchism
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Non-compaction cardiomyopathy
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Cardiac disorders
    Myocarditis
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Nervous system disorders
    Febrile convulsion
         subjects affected / exposed
    0 / 266 (0.00%)
    2 / 521 (0.38%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 2
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Tethered cord syndrome
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Blood and lymphatic system disorders
    Immune thrombocytopenia
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Gastrointestinal disorders
    Enteritis
         subjects affected / exposed
    0 / 266 (0.00%)
    2 / 521 (0.38%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 2
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Incarcerated inguinal hernia
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Infantile diarrhoea
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Inguinal hernia
         subjects affected / exposed
    1 / 266 (0.38%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 2
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Hepatobiliary disorders
    Hepatic function abnormal
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Hyperbilirubinaemia neonatal
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Musculoskeletal and connective tissue disorders
    Tenosynovitis stenosans
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Infections and infestations
    Bronchiolitis
         subjects affected / exposed
    2 / 266 (0.75%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 2
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    COVID-19
         subjects affected / exposed
    2 / 266 (0.75%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 2
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Bronchitis viral
         subjects affected / exposed
    1 / 266 (0.38%)
    2 / 521 (0.38%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 2
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Bronchitis
         subjects affected / exposed
    4 / 266 (1.50%)
    9 / 521 (1.73%)
         occurrences causally related to treatment / all
    0 / 4
    0 / 9
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    COVID-19 pneumonia
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Coronavirus pneumonia
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Cytomegalovirus infection
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Diarrhoea infectious
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Enteritis infectious
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Exanthema subitum
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Gastroenteritis
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Herpes pharyngitis
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Herpangina
         subjects affected / exposed
    3 / 266 (1.13%)
    2 / 521 (0.38%)
         occurrences causally related to treatment / all
    0 / 3
    0 / 2
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Gastroenteritis salmonella
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Influenza
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Laryngitis
         subjects affected / exposed
    1 / 266 (0.38%)
    2 / 521 (0.38%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 3
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Lower respiratory tract infection
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pharyngitis
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Otitis media
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Omphalitis
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pneumonia moraxella
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pneumonia influenzal
         subjects affected / exposed
    2 / 266 (0.75%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 2
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pneumonia haemophilus
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pneumonia
         subjects affected / exposed
    19 / 266 (7.14%)
    17 / 521 (3.26%)
         occurrences causally related to treatment / all
    0 / 22
    0 / 21
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pneumonia mycoplasmal
         subjects affected / exposed
    2 / 266 (0.75%)
    3 / 521 (0.58%)
         occurrences causally related to treatment / all
    0 / 2
    0 / 3
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pneumonia parainfluenzae viral
         subjects affected / exposed
    0 / 266 (0.00%)
    2 / 521 (0.38%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 2
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pneumonia respiratory syncytial viral
         subjects affected / exposed
    1 / 266 (0.38%)
    3 / 521 (0.58%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 3
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pneumonia viral
         subjects affected / exposed
    3 / 266 (1.13%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 3
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Pyelonephritis acute
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Tonsillitis bacterial
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Tonsillitis
         subjects affected / exposed
    1 / 266 (0.38%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Rotavirus infection
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Respiratory syncytial virus bronchiolitis
         subjects affected / exposed
    1 / 266 (0.38%)
    0 / 521 (0.00%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 0
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Upper respiratory tract infection
         subjects affected / exposed
    1 / 266 (0.38%)
    3 / 521 (0.58%)
         occurrences causally related to treatment / all
    0 / 1
    0 / 3
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Urinary tract infection
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Metabolism and nutrition disorders
    Poor feeding infant
         subjects affected / exposed
    0 / 266 (0.00%)
    1 / 521 (0.19%)
         occurrences causally related to treatment / all
    0 / 0
    0 / 1
         deaths causally related to treatment / all
    0 / 0
    0 / 0
    Frequency threshold for reporting non-serious adverse events: 5%
    Non-serious adverse events
    Placebo Nirsevimab
    Total subjects affected by non serious adverse events
         subjects affected / exposed
    222 / 266 (83.46%)
    436 / 521 (83.69%)
    Blood and lymphatic system disorders
    Anaemia
         subjects affected / exposed
    14 / 266 (5.26%)
    21 / 521 (4.03%)
         occurrences all number
    15
    22
    General disorders and administration site conditions
    Pyrexia
         subjects affected / exposed
    55 / 266 (20.68%)
    94 / 521 (18.04%)
         occurrences all number
    66
    111
    Gastrointestinal disorders
    Functional gastrointestinal disorder
         subjects affected / exposed
    17 / 266 (6.39%)
    35 / 521 (6.72%)
         occurrences all number
    22
    42
    Dyspepsia
         subjects affected / exposed
    24 / 266 (9.02%)
    31 / 521 (5.95%)
         occurrences all number
    31
    37
    Diarrhoea
         subjects affected / exposed
    25 / 266 (9.40%)
    55 / 521 (10.56%)
         occurrences all number
    28
    63
    Skin and subcutaneous tissue disorders
    Eczema
         subjects affected / exposed
    29 / 266 (10.90%)
    74 / 521 (14.20%)
         occurrences all number
    38
    81
    Infections and infestations
    Upper respiratory tract infection
         subjects affected / exposed
    174 / 266 (65.41%)
    349 / 521 (66.99%)
         occurrences all number
    348
    744
    Pneumonia
         subjects affected / exposed
    12 / 266 (4.51%)
    27 / 521 (5.18%)
         occurrences all number
    12
    30
    Bronchitis
         subjects affected / exposed
    57 / 266 (21.43%)
    89 / 521 (17.08%)
         occurrences all number
    77
    112

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    Substantial protocol amendments (globally)

    Were there any global substantial amendments to the protocol? Yes
    Date
    Amendment
    22 Apr 2021
    The purpose of this amendment was: To remove the PK parameter estimations because there were few blood samplings points. It was expected that there would be not enough data for non-compartmental analysis. To further reduce the volume of blood collection and to combine 2.5-5 kg and >5 kg due to limited number of infants >5 kg at birth.
    01 Jun 2023
    The purpose of this amendment was: To add the estimands to give a precise description of the treatment effect reflecting the clinical question posed by the objectives, to remove the description which was not implemented in the study execution. To clarify the detail of statistical hypotheses, the efficacy analysis methods of primary and secondary endpoints analysis, and detail of survival analysis. To focus healthcare resource utilisation summaries on the most important aspects of magnitude and the most important efficacy events, especially given the impact on the event numbers from Coronavirus disease-2019 pandemic and to optimise PK/pharmacodynamic samples collect process to avoid duplicated sample collection.
    04 Aug 2025
    The purpose of this amendment was to modify the primary endpoint to all MA RSV LRTI and retain the original primary endpoint as a secondary endpoint, to provide the primary analysis after all participants completed the last visit of the study, to update the sample size justification based on the modified endpoints, to make changes to align with the updated efficacy endpoints and with the summary analyses employed for the secondary endpoints, to remove the secondary estimand details, to add rationale per the requirements of the template, to employ a summary of the incidence of the events for all the secondary efficacy endpoints, to add missing words to ensure that the definition and criteria of objectives were complete, to distinguish the concept of ‘all medically attended LRTI’ from ‘the protocol-defined LRTI’ and to align with the updated primary endpoint, to improve clarity of the description and to keep consistent with the endpoints and their analysis methods, to be consistent with the analysis methods in Global Study MELODY (D5290C00004 [2019-000114-11]) and to clarify that per-protocol analysis would not be conducted based on the guidance of International Council for Harmonisation (ICH) E9 addendum.

    Interruptions (globally)

    Were there any global interruptions to the trial? No

    Limitations and caveats

    Limitations of the trial such as small numbers of subjects analysed or technical problems leading to unreliable data.
    None reported
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    As of 31 January 2023, all EU/EEA initial clinical trial applications must be submitted through CTIS . Updated EudraCT trials information and information on PIP/Art 46 trials conducted exclusively in third countries continues to be submitted through EudraCT and published on this website.

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