The primary objective of the study was to compare the clinical efficacy of high-dose quadrivalent influenza vaccine (QIV-HD) to standard-dose quadrivalent influenza vaccine (QIV-SD) in participants 6 months through 35 months of age for the prevention of laboratory-confirmed influenza illness caused by any influenza A or B type. The secondary objectives of the study were: * To compare QIV-HD to QIV-SD: * in participants 6 months through 35 months of age for the prevention of laboratory-confirmed influenza illness caused by any influenza A or B type using a more stringent threshold * in participants 6 months through 35 months of age for the prevention of laboratory-confirmed protocol-defined influenza-like illness caused by viral strains similar to those contained in the vaccine. * in participants 6 months through 23 months of age for the prevention of laboratory-confirmed influenza illness caused by any influenza A or B types. * To compare hemagglutination inhibition (HAI) immune response of QIV-HD to QIV-SD in participants 6 months through 35 months of age * To describe the HAI, seroneutralization (SN), and anti-neuraminidase (NA) immune response * To describe the immune response to revaccination in Season 3 (Northern Hemisphere) * To describe the safety profile of each vaccine
The study was planned to start in the second half of 2020 with the Sentinel Safety Cohort. Following the Sentinel Safety Cohort, the main efficacy cohort was to be conducted during the 2021-2022 Northern Hemisphere influenza season (Season 1), the 2021-2022 Southern Hemisphere influenza season (Season 2), and the 2021-2022-2023 Northern Hemisphere influenza season (Season 3). Participants received either 1 or 2 doses of the study vaccine depending on whether they were previously influenza vaccinated or previously influenza unvaccinated, respectively. Study duration per participant was approximately 6 to 7 months.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
100
Pharmaceutical form: suspension for injection in a pre-filled syringe; route of administration: intramuscular
Pharmaceutical form: suspension for injection in a pre-filled syringe; route of administration: intramuscular
California Research Foundation Site Number : 8400008
San Diego, California, United States
Acevedo Clinical Research Associates Site Number : 8400007
Miami, Florida, United States
Emory Childrens Center- Site Number : 8400001
Atlanta, Georgia, United States
Heartland El Dorado- Site Number : 8400032
El Dorado, Kansas, United States
Kentucky Pediatrics / Adult Research- Site Number : 8400005
Bardstown, Kentucky, United States
Velocity Clinical Research- New Orleans Site Number : 8400009
New Orleans, Louisiana, United States
Ohio Pediatric Research- Site Number : 8400027
Dayton, Ohio, United States
Rainbow Pediatrics- Site Number : 8400033
Barnwell, South Carolina, United States
Cenexel JBR- Site Number : 8400006
Salt Lake City, Utah, United States
Foothill Family Clinic South- Site Number : 8400045
Salt Lake City, Utah, United States
Number of Participants With Laboratory-Confirmed Influenza Illness Caused by Any Influenza Viral Types/Subtypes
Laboratory-confirmed influenza was a positive influenza result on either polymerase chain reaction (PCR) or viral culture. An influenza-like illness (ILI) was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Viral Strains Similar to Those Contained in the Vaccine
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive in Participants Aged 6 Through 23 Months for Any Influenza A or B Type
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Any Influenza A or B Type According to Previous Vaccination Status
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Viral Strains Similar to Those Contained in the Vaccine According to Previous Vaccination Status
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Any Influenza A or B Type and Associated With Acute Otitis Media (AOM)
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches). The AOM was based on clinical diagnosis.
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Viral Strains Similar to Those Contained in the Vaccine and Associated With Acute Otitis Media
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches). The AOM was based on clinical diagnosis.
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Any Influenza A or B Type and Associated With Acute Lower Respiratory Infection (ALRI)
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches). The ALRI was based on a clinical and/or x-ray diagnosis.
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Viral Strains Similar to Those Contained in the Vaccine and Associated With Acute Lower Respiratory Infection
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches). The ALRI was based on a clinical and/or x-ray diagnosis.
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Polymerase Chain Reaction-Confirmed as Positive for Viral Strains Similar to Those Contained in the Vaccine
The PCR-confirmed influenza was a positive influenza result on PCR. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Culture-Confirmed as Positive for Viral Strains Similar to Those Contained in the Vaccine
Culture-confirmed influenza was a positive influenza result on viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Polymerase Chain Reaction-Confirmed as Positive for Any Influenza A or B Types
The PCR-confirmed influenza was a positive influenza result on PCR. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Culture-Confirmed as Positive for Any Influenza A or B Types
Culture-confirmed influenza was a positive influenza result on viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Any Influenza A or B Types and Associated With Hospitalization
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Number of Participants With Influenza-Like Illness Laboratory-Confirmed as Positive for Viral Strains Similar to Those Contained in the Vaccine and Associated With Hospitalization
Laboratory-confirmed influenza was a positive influenza result on either PCR or viral culture. An ILI was occurrence of fever concurrently with at least 1 of the following symptoms: cough, wheezing, difficulty breathing, nasal congestion, rhinorrhea, pharyngitis (sore throat), otitis, vomiting, diarrhea, shivering (chills), fatigue (tiredness), headache, or myalgia (muscle aches).
Time frame: From 14 days after the first vaccine administration up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 196 days
Geometric Mean Titer of Influenza Vaccine Antibodies
Antibody titers were measured by hemagglutination inhibition (HAI) assay.
Time frame: Days 0 and 56
Number of Participants With Seroconversion
Seroconversion for participants with a pre-vaccination titer \<10 \[1/dilution (dil)\]: Post-injection titer \>=40 (1/dil) on 28 days after the last vaccination or significant increase. Seroconversion for participants with a pre-vaccination titer \>=10 (1/dil): \>=4-fold increase from pre- to post-injection titer on 28 days after the last vaccination. Antibody titers were measured by HAI assay.
Time frame: Days 0 and 56
Number of Participants With Influenza Vaccine Antibody Titer >=10 (1/Dilution)
Antibody titers were measured by HAI assay. The influenza vaccine antibody titer level assessed was \>=10 (1/dil).
Time frame: Days 0 and 56
Influenza Vaccine Antibody Titer Ratio
Antibody titer ratio was calculated as individual antibody titer 28 days after the last vaccination (Day 56) divided by individual antibody titer at Day 0. Antibody titers were measured by HAI assay.
Time frame: Days 0 and 56
Number of Participants With Influenza Vaccine Antibody Titer >=40 (1/Dilution)
Antibody titers were measured by HAI assay. The influenza vaccine antibody titer level assessed was \>=40 (1/dil).
Time frame: Days 0 and 56
Influenza Seroneutralization (SN) Antibody Titer
The antibody titers were measured by the SN method.
Time frame: Days 0 and 56
Influenza Seroneutralization Antibody Titer Ratio
Antibody titer ratio was calculated as fold increase in serum SN post-vaccination relative to Day 0. Antibody titers were measured by the SN method.
Time frame: Day 56
Number of Participants With Influenza Seroneutralization Antibody Titer >=20 (1/Dilution), >=40 (1/Dilution) and >=80 (1/Dilution)
Antibody titers were measured by the SN method. The SN antibody titer levels assessed were \>=20 (1/dil), \>=40 (1/dil) and \>=80 (1/dil).
Time frame: Day 56
Number of Participants With Influenza Seroneutralization Antibody Titer >=2 and >=4 Fold-Rise
Increase of titer levels \>=2 and \>=4 were assessed. Antibody titers were measured by the SN method.
Time frame: Day 56
Detectable Influenza Seroneutralization Antibody Titer
Detectable antibody titers were \>=10 (1/dil). Antibody titers were measured by the SN method.
Time frame: Days 0 and 56
Anti-Neuraminidase (Anti-NA) Antibody Titer
Antibody titers were measured by enzyme-linked lectin assay.
Time frame: Days 0 and 56
Anti-Neuraminidase Antibody Titer Ratio
Antibody titer ratio was calculated as fold increase in anti-NA antibodies post-vaccination relative to Day 0. Antibody titers were measured by enzyme-linked lectin assay.
Time frame: Day 56
Number of Participants With Anti-Neuraminidase Antibody Titer >=20 (1/Dilution), >=40 (1/Dilution) and >=80 (1/Dilution)
Antibody titers were measured by enzyme-linked lectin assay. Anti-NA antibody titer levels assessed were \>=20 (1/dil), \>=40 (1/dil) and \>=80 (1/dil).
Time frame: Day 56
Number of Participants With Anti-Neuraminidase Antibody Titer >=2 and >=4 Fold-Rise
Increase of titer levels \>=2 and \>=4 were assessed. Antibody titers were measured by enzyme-linked lectin assay.
Time frame: Day 56
Detectable Anti-Neuraminidase Antibody Titer
Detectable antibody titers were \>=10 (1/dil). Antibody titers were measured by enzyme-linked lectin assay.
Time frame: Days 0 and 56
Number of Participants With Unsolicited Systemic Adverse Events (AEs) After Each Vaccine Dose Administration
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study vaccine, whether or not considered related to the study vaccine. Immediate events were recorded to capture medically relevant unsolicited systemic AEs which occurred within the first 30 minutes after vaccination. An unsolicited AE was an observed AE that did not fulfill the conditions of solicited reactions, that is, pre-listed in the case report form in terms of diagnosis and onset window post-vaccination.
Time frame: Within 30 minutes after each vaccine administration (vaccines administered at Days 0 and 28)
Number of Participants With Solicited Injection Site Reactions After Each Vaccine Dose Administration
A solicited reaction was an "expected" adverse reaction (AR) (sign or symptom) observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form, and were considered to be related to the study vaccine administered. An injection site reaction was an AR at and around the injection site of the study vaccine.
Time frame: Within 7 days after each vaccine administration (vaccines administered at Days 0 and 28)
Number of Participants With Solicited Systemic Reactions After Each Vaccine Dose Administration
A solicited reaction was an "expected" AR (sign or symptom) observed and reported under the conditions (nature and onset) pre-listed in the protocol and case report form, and were considered to be related to the study vaccine administered. Systemic AR were all ARs that were not injection site reactions.
Time frame: Within 7 days after each vaccine administration (vaccines administered at Days 0 and 28)
Number of Participants With Unsolicited Adverse Events After Each Vaccine Dose Administration
An AE was any untoward medical occurrence in a clinical study participant, temporally associated with the use of study vaccine, whether or not considered related to the study vaccine. An unsolicited AE was an observed AE that did not fulfill the conditions of solicited reactions, that is, pre-listed in the case report form in terms of diagnosis and onset window post-vaccination.
Time frame: Within 28 days after each vaccine administration (vaccines administered at Days 0 and 28)
Number of Participants With Serious Adverse Events (SAEs) and Adverse Events of Special Interest (AESIs)
An SAE was defined as any AE that at any dose resulted in death, was life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, was a congenital anomaly/birth defect, or was an important medical event. An AESI (serious or non-serious) was 1 of scientific and medical concern specific to the Sponsor's study vaccine or program, for which ongoing monitoring and rapid communication by the Investigator to the Sponsor could be appropriate.
Time frame: From first dose of study vaccine administration (Day 1) up to 6 months after the last vaccine administration (vaccines administered at Days 0 and 28), approximately 210 days
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