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A Study to Evaluate the Immunogenicity of Quadrivalent Live Attenuated Influenza Vaccine (LAIV) in Children

A Randomized, Double-Blind, Active Controlled Study to Evaluate the Immunogenicity of Quadrivalent LAIV in Children

Status
Completed
Phases
Phase 3
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT01091246
Acronym
LAIV
Enrollment
2312
Registered
2010-03-23
Start date
2010-03-31
Completion date
2010-12-31
Last updated
2011-09-26

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Healthy or Stable Chronic Illness

Brief summary

The primary objective of this study is to demonstrate the immunologic noninferiority of Q/LAIV to FluMist in children 2 to 17 years of age.

Detailed description

The randomized, double-blind study was designed to demonstrate the immunologic noninferiority of Q/LAIV compared to FluMist in children 2-17 years by comparing the strain-specific post-dose geometric mean titers of hemagglutination inhibition antibodies. Children were randomized 3:1:1 to receive Q/LAIV or one of two FluMist vaccines. Subjects 9-17 years of age received a single dose, and those 2-8 years of age received two doses one month apart. Serum was obtained 1 month after dose 1 except in influenza vaccine-naive subjects 2-8 years old, when it was obtained after dose 2. Safety and tolerability were also assessed.

Interventions

10 \^7.0 ± 0.5 FFU/dose of each of 4 influenza virus strains: A/H1N1, A/H3N2, B/Yamagata, and B/Victoria

10 \^7.0 ± 0.5 FFU/dose of each of 3 influenza virus strains: A/H1N1, A/H3N2, and B/Yamagata

10 \^7.0 ± 0.5 FFU/dose of each of 3 influenza virus strains: A/H1N1, A/H3N2, and B/Victoria

Sponsors

MedImmune LLC
Lead SponsorINDUSTRY

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
QUADRUPLE (Subject, Caregiver, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender
ALL
Age
2 Years to 17 Years
Healthy volunteers
Yes

Inclusion criteria

* Male or female * Age 2 through 17 years at the time of randomization * Written informed consent and any locally required authorization (eg, HIPAA in the USA, EU Data Privacy Directive in the EU, and written informed assent if applicable) obtained from the subject/legal representative prior to performing any protocol-related procedures, including screening evaluations * Females of childbearing potential, unless surgically sterile (ie, bilateral tubal ligation, bilateral oophorectomy, or hysterectomy), has sterile male partner, is premenarchal, or practices abstinence, must have used an effective method of avoiding pregnancy (including oral, transdermal, or implanted contraceptives, intrauterine device, female condom with spermicide, diaphragm with spermicide, cervical cap with spermicide, or use of a condom with spermicide by the sexual partner) for 30 days prior to the first dose of investigational product, and must agree to continue using such precautions for 60 days after the final dose of investigational product * A subject who is considered by the investigator to be at risk of pregnancy must also have a negative urine pregnancy test at screening and, if screening and Day 0 do not occur on the same day, on the day of vaccination prior to randomization. Investigator judgment is required to assess each subject's need for pregnancy testing * Healthy by medical history and physical examination OR presence of stable underlying chronic medical condition for which hospitalization has not been required in the previous year * Able to complete follow-up period of 180 days post last dose of vaccine as required by the protocol * Subject/legal representative is available by telephone * Child's legal representative is able to understand and comply with the requirements of the protocol, as judged by the investigator

Exclusion criteria

* Acute illness or evidence of significant active infection at randomization; * Fever ≥ 100.4°F (38.0°C) at randomization * History of asthma, or in children \< 5 years of age, history of recurrent wheezing * Any drug therapy from 15 days prior to randomization or expected drug therapy through 28 days post last dose with the exception of the following classes/types of medications, which are allowed: * Contraceptives (change in contraceptive type or method is acceptable as long as guidelines are followed for prevention of pregnancy during change); * Topical corticosteroids, calcineurin inhibitors, or antifungals for uncomplicated dermatitis; * Chronic medications (including those taken on an as-needed basis) that have been well tolerated and were not initiated and/or did not have a dosage change within 90 days prior to randomization. * Current or expected receipt of immunosuppressive medications within a 28 day window around any dose, including an immunosuppressive dose of corticosteroids, which is defined as ≥ 20 mg/day of prednisone or its equivalent, given daily or on alternate days for ≥ 15 days) (intranasal, intra-articular, and topical corticosteroids are permitted); Note: topical corticosteroids for uncomplicated dermatitis may be used throughout the study according to the judgment of the investigator; topical calcineurin inhibitors may be used in accordance with their package insert at entry and during study participation * Receipt of immunoglobulin or blood products within 90 days before randomization into the study or expected receipt during study participation * Receipt of any investigational drug therapy within 28 days prior to Dose 1 or planned receipt of any investigational drug therapy through 90 days after final dosing of investigational product (use of licensed agents for indications not listed in the package insert is permitted) * Receipt of any nonstudy vaccine within 28 days prior to randomization or planned receipt of nonstudy vaccine through 28 days after final dosing * Receipt of any nonstudy seasonal influenza vaccine within 90 days of Dose 1 or planned receipt of nonstudy seasonal influenza vaccine prior to 35 days post last dose of investigational product * Any known immunosuppressive condition or immune deficiency disease including known or suspected infection with human immunodeficiency virus (HIV) * History of allergic disease or reactions likely to be exacerbated by any component of the investigational product including allergy to eggs, egg proteins, gentamicin, or gelatin or serious, life threatening, or severe reactions to previous influenza vaccinations * Use of aspirin or salicylate-containing products within 28 days prior to randomization or expected receipt through 28 days after final vaccination; * History of Guillain-Barré syndrome * Use of antiviral agents with activity against influenza virus (including amantadine, rimantadine, oseltamivir, and zanamivir) within 28 days prior to first dose of investigational product or anticipated use of such agents within 28 days after last scheduled vaccination * Known or suspected mitochondrial encephalomyopathy * Pregnant or lactating female * History of alcohol or drug abuse that, in the opinion of the investigator, would affect the subject's safety or compliance with study * Any condition that, in the opinion of the investigator, might compromise the safety of the subject in the study or would interfere with evaluation of the safety or immunogenicity of the investigational products * Subject, legal representative, or immediate family member of subject who is an employee of the clinical study site or who is otherwise involved with the conduct of the study * A history of epilepsy, seizure, or an evolving neurological condition except that of a single febrile seizure that occurred 3 or more years prior to enrollment would not disqualify a subject Note: an individual who initially is excluded from study participation based on one or more of the above time-limited criteria may be reconsidered for enrollment once the condition has resolved as long as the subject continues to meet all other entry criteria and the same SID number is used

Design outcomes

Primary

MeasureTime frameDescription
The 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.Day 28 post immunogenicity doseNoninferior immune response was defined as having the upper bound of the 2-sided 95% confidence intervals (CIs) for the HAI antibody GMT ratio (FluMist comparator divided by Q/LAIV) ≤ 1.5 for each of the 4 strains. .

Secondary

MeasureTime frameDescription
The Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSeroresponse was defined as a ≥ 4-fold rise in HAI antibody titer from baseline.
Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the A/H3N2 Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSeroresponse was defined as a ≥ 4-fold rise in HAI antibody titer from baseline.
Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the B/Yamagata Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSeroresponse was defined as a ≥ 4-fold rise in HAI antibody titer from baseline.
Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the B/Victoria Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSeroresponse was defined as a ≥ 4-fold rise from baseline.
Percent of Serosusceptible Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSerosusceptible was defined as a baseline HAI titer ≤ 8. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.
Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the A/H3N2 Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSerosusceptible was defined as a baseline HAI titer ≤ 8. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.
Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the B/Yamagata Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSerosusceptible was defined as a baseline HAI titer ≤ 8. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.
Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the B/Victoria Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSerosusceptible was defined as a baseline HAI titer ≤ 8. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.
Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSeronegative was defined as a baseline HAI titer ≤ 4. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.
Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H3N2 Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSeronegative was defined as a baseline HAI titer ≤ 4. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.
Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the B/Yamagata Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSeronegative was defined as a baseline HAI titer ≤ 4. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.
Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the B/Victoria Strain Post Immunogenicity DoseDay 0 and Day 28 post immunogenicity doseSeronegative was defined as a baseline HAI titer ≤ 4. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.
Percent of Participants (Regardless of Serostatus) Who Achieved an A/H1N1 or A/H3N2 Strain-specific HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity dose
Percent of Participants (Regardless of Serostatus) Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity dose
Percent of Participants (Regardless of Serostatus) Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity dose
Percent of Serosusceptible Participants Who Achieved an A/H1N1 HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity doseSerosusceptible was defined as a baseline HAI titer ≤ 8.
Percent of Seronegative Participants Who Achieved an A/H3N2 HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity doseSeronegative was defined as a baseline HAI titer ≤ 4.
Percent of Serosusceptible Participants Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity doseSerosusceptible was defined as a baseline HAI titer ≤ 8.
Percent of Serosusceptible Participants Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity doseSerosusceptible was defined as a baseline HAI titer ≤ 8.
Percent of Seronegative Participants Who Achieved an A/H1N1 HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity doseSeronegative was defined as a baseline HAI titer ≤ 4.
Percent of Seronegative Participants Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity doseSeronegative was defined as a baseline HAI titer ≤ 4.
Percent of Seronegative Participants Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity doseSeronegative was defined as a baseline HAI titer ≤ 4.
Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Days 0-14 Post Dose 1Solicited symptoms were fever ≥ 100.4°F (38.0°C), runny/stuffy nose, sore throat, cough, headache, generalized muscle aches, decreased activity level (lethargy) OR tiredness/weakness, decreased appetite. Collection of specific solicited symptoms (sore throat, headache, generalized muscle aches) was omitted when, according to the judgment of the investigator, the subject was too young to reliably report a particular symptom.
Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Days 0-14 Post Dose 1Solicited symptoms were fever ≥ 100.4°F (38.0°C), runny/stuffy nose, sore throat, cough, headache, generalized muscle aches, decreased activity level (lethargy) OR tiredness/weakness, decreased appetite. Collection of specific solicited symptoms (sore throat, headache, generalized muscle aches) was omitted when, according to the judgment of the investigator, the subject was too young to reliably report a particular symptom.
Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Days 0-14 Post Dose 2Solicited symptoms were fever ≥ 100.4°F (38.0°C), runny/stuffy nose, sore throat, cough, headache, generalized muscle aches, decreased activity level (lethargy) OR tiredness/weakness, decreased appetite. Collection of specific solicited symptoms (sore throat, headache, generalized muscle aches) was omitted when, according to the judgment of the investigator, the subject was too young to reliably report a particular symptom.
Percent of All Participants Experiencing Any Adverse Event From Administration of Investigational Product Through Day 28 Post Dose 1Days 0-28 Post Dose 1Any untoward medical occurrence in a patient or clinical investigation in a subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product.
Percent of Two-dose Participants Experiencing Any Adverse Event From Administration of Investigational Product Through Day 28 Post Dose 1Days 0-28 Post Dose 1Any untoward medical occurrence in a patient or clinical investigation in a subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product.
Percent of Two-dose Participants Experiencing Any Adverse Event From Administration of Dose 2 Through 28 Days Post Dose 2Days 0-28 Post Dose 2Any untoward medical occurrence in a patient or clinical investigation in a subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product.
Percent of All Participants Reporting Any Serious Adverse Event (SAE) From Administration of Investigational Product Through Day 28 Post Dose 1Days 0-28 Post Dose 1SAEs were those AEs that resulted in death; were immediately life threatening; resulted in inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; were a congenital anomaly in the offspring of a participant; or were an important medical event that may not have resulted in death, threatened life, or required hospitalization and that, based on appropriate medical judgement, may have jeopardized the participant and may have required medical or surgical intervention to prevent on the outcomes listed above.
Percent of Two-dose Participants Reporting Any SAE From Administration of Dose 2 During Days 0-28 Post Dose 2Days 0-28 Post Dose 2SAEs were those AEs that resulted in death; were immediately life threatening; resulted in inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; were a congenital anomaly in the offspring of a participant; or were an important medical event that may not have resulted in death, threatened life, or required hospitalization and that, based on appropriate medical judgement, may have jeopardized the participant and may have required medical or surgical intervention to prevent on the outcomes listed above.
Percent of All Participants Reporting Any SAE From Administration of Investigational Product Through 180 Days Post Last DoseDays 0-180 Post Last DoseSAEs were those AEs that resulted in death; were immediately life threatening; resulted in inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; were a congenital anomaly in the offspring of a participant; or were an important medical event that may not have resulted in death, threatened life, or required hospitalization and that, based on appropriate medical judgement, may have jeopardized the participant and may have required medical or surgical intervention to prevent on the outcomes listed above.
Percent of All Participants Reporting Any New Onset Chronic Disease (NOCD) From Administration of Investigational Product Through 180 Days Post Last DoseDays 0-180 Post Last DoseAn NOCD was a newly diagnosed medical condition that was of a chronic, ongoing nature and was assessed by the investigator as medically significant.
Percent of Serosusceptible Participants Who Achieved an A/H3N2 HAI Antibody Titer ≥ 32 Post Immunogenicity DoseDay 28 post immunogenicity doseSerosusceptible was defined as a baseline HAI titer ≤ 8.

Countries

United States

Participant flow

Recruitment details

A total of 2,481 participants provided written informed consent and were screened for the study. Of these, 2,312 participants were randomized into the study between 29Mar2010 to 12May2010 at 97 sites in the USA.

Pre-assignment details

Eligible participants were randomized in a 3:1:1 ratio to receive Q/LAIV, FluMist/B/Yamagata, or FluMist/B/Victoria. Randomization was stratified by age (2 to 8 years, 9 to 17 years). For subjects 2 to 8 years of age only, randomization was also stratified by previous seasonal influenza vaccination history.

Participants by arm

ArmCount
Q/LAIV (MEDI3250)
Q/LAIV (quadrivalent live attenuated influenza vaccine) (MEDI3250) was supplied in the Becton Dickinson (BD) Accuspray device that delivers a 0.2 mL total volume intranasal dose divided into each nostril (ie, administered as 0.1 mL per nostril). Each 0.2 mL dose contained 10\^7.0 ± 0.5 fluorescent focus units (FFU) of each of 4 temperature sensitive, cold-adapted, attenuated, 6:2 resassortant influenza strains (A/H1N1 \[A/South Dakota/6/2007\], A/H3N2 \[A/Uruguay/716/2007\], B/Victoria \[B/Malaysia/2506/2004\], and B/Yamagata \[B/Florida/4/2006\]).
1,385
FluMist/B/Yamagata
FluMist/B/Yamagata (trivalent live attenuated influenza vaccine) was supplied in the BD Accuspray device that delivers a 0.2 mL total volume intranasal dose divided into each nostril (ie, administered as 0.1 mL per nostril). Each 0.2 mL dose contained 10\^7.0 ± 0.5 FFU of each of 3 temperature sensitive, cold-adapted, attenuated, 6:2 reassortant influenza strains (A/H1N1 \[South Dakota/6/2007\], A/H3N2 \[A/Uruguay/716/2007\], and B/Yamagata \[B/Florida/4/2006\]).
464
FluMist/B/Victoria
FluMist/B/Victoria (trivalent live attenuated influenza vaccine) was supplied in the BD Accuspray device that delivers a 0.2 mL total volume intranasal dose divided into each nostril (ie, administered as 0.1 mL per nostril). Each 0.2 mL dose contained 10\^7.0 ± 0.5 FFU of each of 3 temperature sensitive, cold-adapted, attenuated, 6:2 reassortant influenza stains (A/H1N1 \[A/South Dakota/6/2007\], A/H3N2 \[A/Uruguay/716/2007\], and B/Victoria \[B/Malaysia/2506/2004\]).
463
Total2,312

Withdrawals & dropouts

PeriodReasonFG000FG001FG002
Overall StudyAdverse Event101
Overall StudyLost to Follow-up23117
Overall StudySubject not dosed201
Overall StudyWithdrawal by Subject954

Baseline characteristics

CharacteristicQ/LAIV (MEDI3250)FluMist/B/YamagataFluMist/B/VictoriaTotal
Age Continuous6.7 Years
STANDARD_DEVIATION 3.8
6.8 Years
STANDARD_DEVIATION 3.8
6.8 Years
STANDARD_DEVIATION 3.9
6.7 Years
STANDARD_DEVIATION 3.8
Sex: Female, Male
Female
707 Participants229 Participants240 Participants1176 Participants
Sex: Female, Male
Male
678 Participants235 Participants223 Participants1136 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
— / —— / —
other
Total, other adverse events
176 / 1,382105 / 923
serious
Total, serious adverse events
6 / 1,3825 / 923

Outcome results

Primary

The 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.

Noninferior immune response was defined as having the upper bound of the 2-sided 95% confidence intervals (CIs) for the HAI antibody GMT ratio (FluMist comparator divided by Q/LAIV) ≤ 1.5 for each of the 4 strains. .

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FY=464; FV=463; All FM=927), had post dose HAI antibody measurement at the appropriate time and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response (Q=1327; FY=445; FV=437; All FM=883).

ArmMeasureGroupValue (GEOMETRIC_MEAN)
Q/LAIV (MEDI3250)The 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.B/Victoria35.4 Geometric mean titer
Q/LAIV (MEDI3250)The 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.A/H3N227.7 Geometric mean titer
Q/LAIV (MEDI3250)The 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.B/Yamagata49.6 Geometric mean titer
Q/LAIV (MEDI3250)The 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.A/H1N116.7 Geometric mean titer
FluMist/B/YamagataThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.A/H3N2NA Geometric mean titer
FluMist/B/YamagataThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.B/VictoriaNA Geometric mean titer
FluMist/B/YamagataThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.B/Yamagata59.8 Geometric mean titer
FluMist/B/YamagataThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.A/H1N1NA Geometric mean titer
FluMist/B/VictoriaThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.B/YamagataNA Geometric mean titer
FluMist/B/VictoriaThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.A/H3N2NA Geometric mean titer
FluMist/B/VictoriaThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.A/H1N1NA Geometric mean titer
FluMist/B/VictoriaThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.B/Victoria37.0 Geometric mean titer
All FluMist GroupThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.B/VictoriaNA Geometric mean titer
All FluMist GroupThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.A/H3N228.8 Geometric mean titer
All FluMist GroupThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.B/YamagataNA Geometric mean titer
All FluMist GroupThe 4 Post-dose Strain-specific Serum Hemagglutination Inhibition (HAI) Antibody Geometric Mean Titers (GMT) in the Q/LAIV (MEDI3250) Arm Are Noninferior to Those in the Comparator FluMist Group.A/H1N117.9 Geometric mean titer
Comparison: B/Victoria: The statistical hypothesis testing for the primary endpoint for Q/LAIV was: H0: Rj \> 1.5, for any j HA: Rj ≤ 1.5, for all j Where Rj was any of the 4 strain-specific post immunogenicity dose GMT ratios: (FluMist/B/Victoria) / (Q/LAIV) for B/Victoria strain95% CI: [0.93, 1.18]
Comparison: A/H1N1: The statistical hypothesis testing for the primary endpoint for Q/LAIV was: H0: Rj \> 1.5, for any j HA: Rj ≤ 1.5, for all j Where Rj was any of the 4 strain-specific post immunogenicity dose GMT ratios: (FluMist/B/Yamagata + FluMist/B/Victoria) / (Q/LAIV) for A/H1N1 strain95% CI: [0.98, 1.16]Bootstrapping
Comparison: A/H3N2: The statistical hypothesis testing for the primary endpoint for Q/LAIV was: H0: Rj \> 1.5, for any j HA: Rj ≤ 1.5, for all j Where Rj was any of the 4 strain-specific post immunogenicity dose GMT ratios: (FluMist/B/Yamagata + FluMist/B/Victoria) / (Q/LAIV) for A/H3N2 strain95% CI: [0.94, 1.14]Bootstrapping
Comparison: B/Yamagata: The statistical hypothesis testing for the primary endpoint for Q/LAIV was: H0: Rj \> 1.5, for any j HA: Rj ≤ 1.5, for all j Where Rj was any of the 4 strain-specific post immunogenicity dose GMT ratios: (FluMist/B/Yamagata) / (Q/LAIV) for B/Yamagata strain95% CI: [1.07, 1.37]
Secondary

Percent of All Participants Experiencing Any Adverse Event From Administration of Investigational Product Through Day 28 Post Dose 1

Any untoward medical occurrence in a patient or clinical investigation in a subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product.

Time frame: Days 0-28 Post Dose 1

Population: All participants who received any investigational product (Q=1385; All FM=927) and for whom any safety data were recorded during the summarized period (Q=1382; All FM=923).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Any Adverse Event From Administration of Investigational Product Through Day 28 Post Dose 121.0 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Any Adverse Event From Administration of Investigational Product Through Day 28 Post Dose 120.7 Percent of Participants
Secondary

Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1

Solicited symptoms were fever ≥ 100.4°F (38.0°C), runny/stuffy nose, sore throat, cough, headache, generalized muscle aches, decreased activity level (lethargy) OR tiredness/weakness, decreased appetite. Collection of specific solicited symptoms (sore throat, headache, generalized muscle aches) was omitted when, according to the judgment of the investigator, the subject was too young to reliably report a particular symptom.

Time frame: Days 0-14 Post Dose 1

Population: All participants who received any investigational product (Q=1385; All FM=927) and for whom any follow-up solicited symptom safety data were recorded during the summarized period (Q=1377; All FM=920).

ArmMeasureGroupValue (NUMBER)
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Any solicited symptom47.9 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 100.4°F (38.0°C)5.7 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 101.3°F (38.5°C)3.3 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 102.2°F (39.0°C)1.4 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 103.1°F (39.5°C)0.3 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 104.0°F (40.0°C)0.1 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 104.9°F (40.5°C)0.0 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Runny/stuffy nose32.3 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Sore throat9.2 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Cough15.8 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Headache12.5 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Generalized muscle aches4.4 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Decreased activity level or tiredness/weakness9.8 Percent of Participants
Q/LAIV (MEDI3250)Percent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Decreased appetite5.5 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Headache12.2 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Any solicited symptom47.4 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Runny/stuffy nose32.0 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 100.4°F (38.0°C)3.9 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Decreased activity level or tiredness/weakness9.9 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 101.3°F (38.5°C)2.3 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Sore throat10.3 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 102.2°F (39.0°C)0.8 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Generalized muscle aches4.6 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 103.1°F (39.5°C)0.2 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Cough16.8 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 104.0°F (40.0°C)0.0 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Decreased appetite6.6 Percent of Participants
FluMist/B/YamagataPercent of All Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 104.9°F (40.5°C)0.0 Percent of Participants
Secondary

Percent of All Participants Reporting Any New Onset Chronic Disease (NOCD) From Administration of Investigational Product Through 180 Days Post Last Dose

An NOCD was a newly diagnosed medical condition that was of a chronic, ongoing nature and was assessed by the investigator as medically significant.

Time frame: Days 0-180 Post Last Dose

Population: All participants who received any investigational product (Q=1385; All FM=927) and for whom any safety data were recorded during the summarized period (Q=1382; All FM=923).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of All Participants Reporting Any New Onset Chronic Disease (NOCD) From Administration of Investigational Product Through 180 Days Post Last Dose1.4 Percent of participants
FluMist/B/YamagataPercent of All Participants Reporting Any New Onset Chronic Disease (NOCD) From Administration of Investigational Product Through 180 Days Post Last Dose0.8 Percent of participants
Secondary

Percent of All Participants Reporting Any SAE From Administration of Investigational Product Through 180 Days Post Last Dose

SAEs were those AEs that resulted in death; were immediately life threatening; resulted in inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; were a congenital anomaly in the offspring of a participant; or were an important medical event that may not have resulted in death, threatened life, or required hospitalization and that, based on appropriate medical judgement, may have jeopardized the participant and may have required medical or surgical intervention to prevent on the outcomes listed above.

Time frame: Days 0-180 Post Last Dose

Population: All participants who received any investigational product (Q=1385; All FM=927) and for whom any safety data were recorded during the summarized period (Q=1382; All FM=923).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of All Participants Reporting Any SAE From Administration of Investigational Product Through 180 Days Post Last Dose0.4 Percent of participants
FluMist/B/YamagataPercent of All Participants Reporting Any SAE From Administration of Investigational Product Through 180 Days Post Last Dose0.5 Percent of participants
Secondary

Percent of All Participants Reporting Any Serious Adverse Event (SAE) From Administration of Investigational Product Through Day 28 Post Dose 1

SAEs were those AEs that resulted in death; were immediately life threatening; resulted in inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; were a congenital anomaly in the offspring of a participant; or were an important medical event that may not have resulted in death, threatened life, or required hospitalization and that, based on appropriate medical judgement, may have jeopardized the participant and may have required medical or surgical intervention to prevent on the outcomes listed above.

Time frame: Days 0-28 Post Dose 1

Population: All participants who received any investigational product (Q=1385; All FM=927) and for whom any safety data were recorded during the summarized period (Q=1382; All FM=923).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of All Participants Reporting Any Serious Adverse Event (SAE) From Administration of Investigational Product Through Day 28 Post Dose 10.0 Percent of participants
FluMist/B/YamagataPercent of All Participants Reporting Any Serious Adverse Event (SAE) From Administration of Investigational Product Through Day 28 Post Dose 10.0 Percent of participants
Secondary

Percent of Participants (Regardless of Serostatus) Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FV=463), had post dose HAI antibody measurement at the appropriate time, and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response (Q=1327; FV=437).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Participants (Regardless of Serostatus) Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose65.6 Percent of participants
FluMist/B/YamagataPercent of Participants (Regardless of Serostatus) Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose66.6 Percent of participants
Secondary

Percent of Participants (Regardless of Serostatus) Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FY=464), had post dose HAI antibody measurement at the appropriate time, and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response (Q=1327; FY=445).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Participants (Regardless of Serostatus) Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose76.5 Percent of participants
FluMist/B/YamagataPercent of Participants (Regardless of Serostatus) Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose81.6 Percent of participants
Secondary

Percent of Participants (Regardless of Serostatus) Who Achieved an A/H1N1 or A/H3N2 Strain-specific HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response (Q=1327; All FM=883).

ArmMeasureGroupValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Participants (Regardless of Serostatus) Who Achieved an A/H1N1 or A/H3N2 Strain-specific HAI Antibody Titer ≥ 32 Post Immunogenicity DoseA/H1N143.1 Percent of participants
Q/LAIV (MEDI3250)Percent of Participants (Regardless of Serostatus) Who Achieved an A/H1N1 or A/H3N2 Strain-specific HAI Antibody Titer ≥ 32 Post Immunogenicity DoseA/H3N255.7 Percent of participants
FluMist/B/YamagataPercent of Participants (Regardless of Serostatus) Who Achieved an A/H1N1 or A/H3N2 Strain-specific HAI Antibody Titer ≥ 32 Post Immunogenicity DoseA/H1N143.8 Percent of participants
FluMist/B/YamagataPercent of Participants (Regardless of Serostatus) Who Achieved an A/H1N1 or A/H3N2 Strain-specific HAI Antibody Titer ≥ 32 Post Immunogenicity DoseA/H3N255.4 Percent of participants
Secondary

Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose

Seroresponse was defined as a ≥ 4-fold rise in HAI antibody titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response (Q=1321; All FM=879).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose3.9 Percent of participants
FluMist/B/YamagataPercent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose3.6 Percent of participants
Secondary

Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the B/Victoria Strain Post Immunogenicity Dose

Seroresponse was defined as a ≥ 4-fold rise from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FV=463), had post dose HAI antibody measurement at the appropriate time, and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response (Q=1321; FV=437).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the B/Victoria Strain Post Immunogenicity Dose39.1 Percent of participants
FluMist/B/YamagataPercent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the B/Victoria Strain Post Immunogenicity Dose38.4 Percent of participants
Secondary

Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose

Seroresponse was defined as a ≥ 4-fold rise in HAI antibody titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FY=464), had post dose HAI antibody measurement at the appropriate time, and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response (Q=1321; FY=441).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose43.4 Percent of participants
FluMist/B/YamagataPercent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose44.9 Percent of participants
Secondary

Percent of Seronegative Participants Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Seronegative was defined as a baseline HAI titer ≤ 4.

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FY=464), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were seronegative to the strain (Q=487; FV=159).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Seronegative Participants Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose37.0 Percent of Participants
FluMist/B/YamagataPercent of Seronegative Participants Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose42.8 Percent of Participants
Secondary

Percent of Seronegative Participants Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Seronegative was defined as a baseline HAI titer ≤ 4.

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FY=464), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were seronegative to the strain (Q=483; FY=165).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Seronegative Participants Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose60.9 Percent of participants
FluMist/B/YamagataPercent of Seronegative Participants Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose70.9 Percent of participants
Secondary

Percent of Seronegative Participants Who Achieved an A/H1N1 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Seronegative was defined as a baseline HAI titer ≤ 4.

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were seronegative to the strain (Q=460; All FM=321).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Seronegative Participants Who Achieved an A/H1N1 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose5.2 Percent of participants
FluMist/B/YamagataPercent of Seronegative Participants Who Achieved an A/H1N1 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose5.6 Percent of participants
Secondary

Percent of Seronegative Participants Who Achieved an A/H3N2 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Seronegative was defined as a baseline HAI titer ≤ 4.

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were seronegative to the strain (Q=364; All FM=244).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Seronegative Participants Who Achieved an A/H3N2 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose3.8 Percent of participants
FluMist/B/YamagataPercent of Seronegative Participants Who Achieved an A/H3N2 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose4.9 Percent of participants
Secondary

Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose

Seronegative was defined as a baseline HAI titer ≤ 4. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response and were seronegative to the strain (Q=460; All FM=321).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose14.6 Percent of participants
FluMist/B/YamagataPercent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose19.6 Percent of participants
Secondary

Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose

Seronegative was defined as a baseline HAI titer ≤ 4. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response and were seronegative to the strain (Q=364; All FM=244).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose9.9 Percent of participants
FluMist/B/YamagataPercent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose11.1 Percent of participants
Secondary

Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the B/Victoria Strain Post Immunogenicity Dose

Seronegative was defined as a baseline HAI titer ≤ 4. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FV=463), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were seronegative to the strain (Q=487; FV=159).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the B/Victoria Strain Post Immunogenicity Dose68.8 Percent of participants
FluMist/B/YamagataPercent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the B/Victoria Strain Post Immunogenicity Dose73.6 Percent of participants
Secondary

Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose

Seronegative was defined as a baseline HAI titer ≤ 4. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FY=464), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were seronegative to the strain (Q=483; FY=165).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose83.0 Percent of participants
FluMist/B/YamagataPercent of Seronegative Participants Within Each Treatment Arm Who Experienced a Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose84.8 Percent of participants
Secondary

Percent of Serosusceptible Participants Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Serosusceptible was defined as a baseline HAI titer ≤ 8.

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FV=463), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were serosusceptible to the strain (Q=620; FV=191).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Serosusceptible Participants Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose41.1 Percent of participants
FluMist/B/YamagataPercent of Serosusceptible Participants Who Achieved a B/Victoria HAI Antibody Titer ≥ 32 Post Immunogenicity Dose44.0 Percent of participants
Secondary

Percent of Serosusceptible Participants Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Serosusceptible was defined as a baseline HAI titer ≤ 8.

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FY=464), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were serosusceptible to the strain (Q=588; FY=192).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Serosusceptible Participants Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose60.9 Percent of participants
FluMist/B/YamagataPercent of Serosusceptible Participants Who Achieved a B/Yamagata HAI Antibody Titer ≥ 32 Post Immunogenicity Dose69.3 Percent of participants
Secondary

Percent of Serosusceptible Participants Who Achieved an A/H1N1 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Serosusceptible was defined as a baseline HAI titer ≤ 8.

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were serosusceptible to the strain (Q=569; All FM=392).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Serosusceptible Participants Who Achieved an A/H1N1 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose5.1 Percent of participants
FluMist/B/YamagataPercent of Serosusceptible Participants Who Achieved an A/H1N1 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose6.1 Percent of participants
Secondary

Percent of Serosusceptible Participants Who Achieved an A/H3N2 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose

Serosusceptible was defined as a baseline HAI titer ≤ 8.

Time frame: Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were serosusceptible to the strain (Q=435; All FM=298).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Serosusceptible Participants Who Achieved an A/H3N2 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose4.8 Percent of participants
FluMist/B/YamagataPercent of Serosusceptible Participants Who Achieved an A/H3N2 HAI Antibody Titer ≥ 32 Post Immunogenicity Dose4.4 Percent of participants
Secondary

Percent of Serosusceptible Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose

Serosusceptible was defined as a baseline HAI titer ≤ 8. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were serosusceptible to the strain (Q=569; All FM=392).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Serosusceptible Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose12.7 Percent of participants
FluMist/B/YamagataPercent of Serosusceptible Participants Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose17.6 Percent of participants
Secondary

Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose

Serosusceptible was defined as a baseline HAI titer ≤ 8. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were serosusceptible to the strain (Q=435; All FM=298).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose9.9 Percent of participants
FluMist/B/YamagataPercent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the A/H3N2 Strain Post Immunogenicity Dose9.4 Percent of participants
Secondary

Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the B/Victoria Strain Post Immunogenicity Dose

Serosusceptible was defined as a baseline HAI titer ≤ 8. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FV=463), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were serosusceptible to the strain (Q=620; FV=191).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the B/Victoria Strain Post Immunogenicity Dose66.1 Percent of participants
FluMist/B/YamagataPercent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the B/Victoria Strain Post Immunogenicity Dose69.6 Percent of participants
Secondary

Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose

Serosusceptible was defined as a baseline HAI titer ≤ 8. Seroresponse was defined as a ≥ 4-fold rise in HAI titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; FY=464), had post dose HAI antibody measurement at the appropriate time, had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response, and were serosusceptible to the strain (Q=588; FY=192).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose79.1 Percent of participants
FluMist/B/YamagataPercent of Serosusceptible Participants Within Each Treatment Arm Who Experience Seroresponse to the B/Yamagata Strain Post Immunogenicity Dose81.3 Percent of participants
Secondary

Percent of Two-dose Participants Experiencing Any Adverse Event From Administration of Dose 2 Through 28 Days Post Dose 2

Any untoward medical occurrence in a patient or clinical investigation in a subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product.

Time frame: Days 0-28 Post Dose 2

Population: All two-dose participants who received any investigational product (Q=1083; All FM=719) and for whom any post Dose 2 safety data were recorded during the summariezed period (Q=1041; All FM=693).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Any Adverse Event From Administration of Dose 2 Through 28 Days Post Dose 213.4 Percent of participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Any Adverse Event From Administration of Dose 2 Through 28 Days Post Dose 216.7 Percent of participants
Secondary

Percent of Two-dose Participants Experiencing Any Adverse Event From Administration of Investigational Product Through Day 28 Post Dose 1

Any untoward medical occurrence in a patient or clinical investigation in a subject administered a pharmaceutical product and which does not necessarily have a causal relationship with this treatment. An AE can therefore be any unfavorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product.

Time frame: Days 0-28 Post Dose 1

Population: All two-dose participants who received any investigational product (Q=1083; All FM=719) and for whom any safety data were recorded during the summarized period (Q=1083; All FM=719).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Any Adverse Event From Administration of Investigational Product Through Day 28 Post Dose 120.3 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Any Adverse Event From Administration of Investigational Product Through Day 28 Post Dose 122.9 Percent of Participants
Secondary

Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2

Solicited symptoms were fever ≥ 100.4°F (38.0°C), runny/stuffy nose, sore throat, cough, headache, generalized muscle aches, decreased activity level (lethargy) OR tiredness/weakness, decreased appetite. Collection of specific solicited symptoms (sore throat, headache, generalized muscle aches) was omitted when, according to the judgment of the investigator, the subject was too young to reliably report a particular symptom.

Time frame: Days 0-14 Post Dose 2

Population: All two-dose participants who received any investigational product (Q=1083; All FM=719) and for whom any follow-up solicited symptom safety data were recorded during the summarized period (Q=1039; All FM=692).

ArmMeasureGroupValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 102.2°F (39.0°C)0.8 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Runny/stuffy nose20.9 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Any solicited symptom31.4 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Sore throat4.1 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 103.1°F (39.5°C)0.3 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Cough12.7 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 101.3°F (38.5°C)1.5 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Headache5.4 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 104.0°F (40.0°C)0.0 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 100.4°F (38.0°C)2.7 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Decreased activity level or tiredness/weakness5.9 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 104.9°F (40.5°C)0.0 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Decreased appetite3.7 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Generalized muscle aches1.2 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Decreased appetite3.3 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Any solicited symptom30.6 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 100.4°F (38.0°C)4.2 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 101.3°F (38.5°C)2.3 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 102.2°F (39.0°C)1.0 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 103.1°F (39.5°C)0.3 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 104.0°F (40.0°C)0.1 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Fever ≥ 104.9°F (40.5°C)0.0 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Runny/stuffy nose19.5 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Sore throat4.6 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Cough11.7 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Headache5.5 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Generalized muscle aches0.9 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Dose 2 During Days 0-14 Post Dose 2Decreased activity level or tiredness/weakness5.3 Percent of Participants
Secondary

Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1

Solicited symptoms were fever ≥ 100.4°F (38.0°C), runny/stuffy nose, sore throat, cough, headache, generalized muscle aches, decreased activity level (lethargy) OR tiredness/weakness, decreased appetite. Collection of specific solicited symptoms (sore throat, headache, generalized muscle aches) was omitted when, according to the judgment of the investigator, the subject was too young to reliably report a particular symptom.

Time frame: Days 0-14 Post Dose 1

Population: All two-dose participants who received any investigational product (Q=1083; All FM=719) and for whom any follow-up solicited symptom safety data were recorded during the summarized period (Q=1078; All FM=716).

ArmMeasureGroupValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Any solicited symptom48.1 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 100.4°F (38.0°C)6.6 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 101.3°F (38.5°C)4.0 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 102.2°F (39.0°C)1.7 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 103.1°F (39.5°C)0.4 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 104.0°F (40.0°C)0.1 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 104.9°F (40.5°C)0.0 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Runny/stuffy nose33.8 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Sore throat8.2 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Cough17.2 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Headache9.7 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Generalized muscle aches4.5 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Decreased activity level or tiredness/weakness9.3 Percent of Participants
Q/LAIV (MEDI3250)Percent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Decreased appetite5.6 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Headache10.1 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Any solicited symptom47.5 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Runny/stuffy nose31.7 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 100.4°F (38.0°C)4.2 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Decreased activity level or tiredness/weakness8.2 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 101.3°F (38.5°C)2.2 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Sore throat8.9 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 102.2°F (39.0°C)0.8 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Generalized muscle aches4.3 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 103.1°F (39.5°C)0.3 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Cough18.0 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 104.0°F (40.0°C)0.0 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Decreased appetite6.7 Percent of Participants
FluMist/B/YamagataPercent of Two-dose Participants Experiencing Each Solicited Symptom From Administration of Investigational Product Through 14 Days Post Dose 1Fever ≥ 104.9°F (40.5°C)0.0 Percent of Participants
Secondary

Percent of Two-dose Participants Reporting Any SAE From Administration of Dose 2 During Days 0-28 Post Dose 2

SAEs were those AEs that resulted in death; were immediately life threatening; resulted in inpatient hospitalization or prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; were a congenital anomaly in the offspring of a participant; or were an important medical event that may not have resulted in death, threatened life, or required hospitalization and that, based on appropriate medical judgement, may have jeopardized the participant and may have required medical or surgical intervention to prevent on the outcomes listed above.

Time frame: Days 0-28 Post Dose 2

Population: All two-dose participants who received any investigational product (Q=1083; All FM=719) and for whom any post Dose 2 safety data were recorded during the summarized period (Q=1041; All FM=693).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)Percent of Two-dose Participants Reporting Any SAE From Administration of Dose 2 During Days 0-28 Post Dose 20.2 Percent of participants
FluMist/B/YamagataPercent of Two-dose Participants Reporting Any SAE From Administration of Dose 2 During Days 0-28 Post Dose 20.1 Percent of participants
Secondary

The Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose

Seroresponse was defined as a ≥ 4-fold rise in HAI antibody titer from baseline.

Time frame: Day 0 and Day 28 post immunogenicity dose

Population: All participants who received any investigational product (Q=1385; All FM=927), had post dose HAI antibody measurement at the appropriate time, and had no protocol deviation judged to have the potential to interfere with the generation or interpretation of an immune response (Q=1320; All FM=878).

ArmMeasureValue (NUMBER)
Q/LAIV (MEDI3250)The Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose6.3 percent of participants
FluMist/B/YamagataThe Percent of Participants (Regardless of Serostatus) Within Each Treatment Arm Who Experienced a Seroresponse to the A/H1N1 Strain Post Immunogenicity Dose8.2 percent of participants

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026