Study of a Single Intramuscular Dose of Nirsevimab in the Prevention of Hospitalizations Due to Respiratory Syncytial Virus (RSV) Infection in Healthy Term and Preterm Infants During the First Year of Life

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths per minute (/min); 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. RSV season was the period of increased RSV infection.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Very severe RSV LRTI was defined as RSV LRTI hospitalization with oxygen saturation <90% (at any time during hospitalization) and oxygen supplementation. Hospitalization was defined as the decision to admit to in-patient care by the treating physician. RSV season was the period of increased RSV infection.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. RSV season was the period of increased RSV infection. Number of participants with RSV LRTI hospitalization through the RSV season in France, UK, and Germany is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. RSV season was the period of increased RSV infection. Number of participants with hospitalization for all-cause LRTI through the RSV season in France, UK, Germany, and overall is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with RSV LRTI hospitalization through 151 days post-dosing/randomization in France, UK, Germany, and overall is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Very severe RSV LRTI was defined as RSV LRTI hospitalization with oxygen saturation <90% (at any time during hospitalization) and oxygen supplementation. Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with very severe RSV LRTI through 151 days post-dosing/randomization in France, UK, Germany, and overall is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with hospitalization for all-cause LRTI through 151 days post-dosing/randomization in France, UK, Germany, and overall is presented.

An adverse event (AE) was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. TEAEs were either events with the start date and time posterior to the start of the treatment period and up to the end of the treatment period or events with the start date and time prior to the start of the treatment period, whose severity was greater than 1 or missing and stop date is missing or not before the treatment period. Immediate events were recorded to capture medically relevant AEs which occurred within the first 30 minutes after immunization.

An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. TEAEs were either events with the start date and time posterior to the start of the treatment period and up to the end of the treatment period or events with the start date and time prior to the start of the treatment period, whose severity was greater than 1 or missing and stop date was missing or not before the treatment period.

AE: untoward medical occurrence in clinical study participant, temporally associated with use of study intervention, whether or not related to it. TEAEs: events with start date/time posterior to start of treatment period(TP) and up to end of TP, or events with start date/time prior to start of TP, whose severity was>1/missing; stop date was missing/not before TP. SAE: AE at any dose resulting in death, persistent or significant disability/incapacity, required inpatient hospitalization/prolongation of existing hospitalization, was life-threatening or congenital anomaly/birth defect or medically important event. MAAE: new onset/worsening of condition that prompted participant or participant's parent/legally acceptable representative to seek unplanned medical advice at physician's office/Emergency Department. AESI: scientific, medical concern specific to Sponsor's study intervention/program for which ongoing monitoring and rapid communication by investigator to Sponsor was appropriate.

An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study intervention, whether or not considered related to the study intervention. TEAEs were either events with the start date and time posterior to the start of the treatment period and up to the end of the treatment period or events with the start date and time prior to the start of the treatment period, whose severity was greater than 1 or missing and stop date is missing or not before the treatment period. SAE: AE at any dose resulting in death, persistent or significant disability/incapacity, required inpatient hospitalization/prolongation of existing hospitalization, was life-threatening or congenital anomaly/birth defect or medically important event. A treatment-related TEAE was a TEAE considered by the investigator as related or with unknown/missing relationship to treatment for participants who received nirsevimab on Day 1.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with RSV LRTI hospitalization through 181 days post-dosing/randomization in France, UK, Germany, and overall is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with hospitalization for all-cause LRTI through 181 days post-dosing/randomization in France, UK, Germany, and overall is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with RSV LRTI hospitalization from Days 181 to 366 post-dosing/randomization (with no RSV LRTI hospitalizations before Day 181) in France, UK, Germany, and overall is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with hospitalization for all-cause LRTI from Days 181 to 366 post-dosing/randomization (with no hospitalizations for all-cause LRTI before Day 181) is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with RSV LRTI hospitalization from Days 366 to 731 post-dosing/randomization (with no RSV LRTI hospitalizations before Day 366) in UK reconsented participants is presented.

LRTI included the following common symptoms: clinical finding of rhonchi, rales, crackles, or wheeze; increased respiratory rate at rest (age: <2 months, ≥60 breaths/min; 2 to 6 months, ≥50 breaths/min; >6 months, ≥40 breaths/min), and hypoxemia (in room air: oxygen saturation <95%). Hospitalization was defined as the decision to admit to in-patient care by the treating physician. Number of participants with hospitalization for all-cause LRTI from Days 366 to 731 post-dosing/randomization (with no hospitalizations for all-cause LRTI before Day 366) in UK reconsented participants is presented.

Wheeze was defined as a physician-diagnosed wheeze or asthma or related ear, nose and throat (ENT)/respiratory symptoms at an office visit or an illness for which the child was prescribed medication to treat an ENT/respiratory condition. Recurrent wheeze event was defined as 2 or more protocol-defined wheeze episodes throughout follow-up period.