This is a Phase 3, randomized, observer-blinded study to evaluate the efficacy, safety, tolerability, and immunogenicity of a single dose of a quadrivalent influenza modRNA vaccine compared to licensed inactivated influenza vaccine in healthy adults 18 years of age and older.
This is a Phase 3, randomized, observer-blinded study to evaluate the efficacy, safety, tolerability, and immunogenicity of a quadrivalent influenza modRNA vaccine (qIRV) encoding HA of 4 seasonally recommended strains (2 A strains and 2 B strains) compared to licensed quadrivalent influenza vaccine (QIV) in healthy adults 18 years of age and older. Participants may be enrolled in either the reactogenicity subset, immunogenicity subset, or both/neither subset(s). Efficacy will be assessed in this study through surveillance for influenza-like illness.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
PREVENTION
Masking
QUADRUPLE
Enrollment
45,789
Quadrivalent influenza modRNA vaccine (single dose)
Licensed quadrivalent influenza vaccine (single dose)
Percentage of Participants Reporting First Episode of LCI Cases With Associated Per-Protocol ILI Caused by Any Strain at Least 14 Days After Vaccination: 18-64 Years
LCI was defined as influenza infection confirmed through through reverse transcription- polymerase chain reaction (RT-PCR) or culture at the central laboratory, unless otherwise specified. Per-protocol ILI was defined as occurrence (new onset or worsening of preexisting condition) of at least 1 respiratory symptoms concurrently with at least 1 systemic symptoms. Data was obtained during the 2022-2023 northern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 to surveillance cut-off (approximately 6 months)
Percentage of Participants Reporting First Episode of Laboratory-Confirmed Influenza (LCI) Cases With Associated Per-Protocol Influenza-Like Illness (ILI) Caused by Any Strain at Least 14 Days After Vaccination: >= 65 Years
LCI was defined as influenza infection confirmed through RT-PCR or culture at the central laboratory, unless otherwise specified. Per-protocol ILI was defined as occurrence (new onset or worsening of preexisting condition) of at least 1 respiratory symptoms concurrently with at least 1 systemic symptoms. Data was obtained during the 2022-2023 northern and southern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 up to primary surveillance cut-off (approximately 1 year)
Percentage of Participants Reporting Any Local Reactions Within 7 Days After Study Vaccination: 18-64 Years
Local reactions included redness, swelling and pain at the injection site and were recorded by participants in an e-diary. All local reactions were graded based on Center for Biologics Evaluation and Research (CBER) toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure data is reported for any local reaction and any grade.
Time frame: From Day 1 to Day 7 after study vaccination
Percentage of Participants Reporting Any Local Reactions Within 7 Days After Study Vaccination: >=65 Years
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.
North Alabama Research Center
Athens, Alabama, United States
St. Vincent's Birmingham Hospital
Birmingham, Alabama, United States
Accel Research Sites Network - Birmingham Clinical Research Unit
Birmingham, Alabama, United States
Ross Bridge Medical Practice, LLC-CCT Research
Birmingham, Alabama, United States
SEC Clinical Research
Dothan, Alabama, United States
Lakeview Clinical Research
Guntersville, Alabama, United States
Medical Affiliated Research Center
Huntsville, Alabama, United States
Lenzmeier Family Medicine/CCT Research
Glendale, Arizona, United States
Aventiv Research
Mesa, Arizona, United States
Desert Clinical Research/ CCT Research
Mesa, Arizona, United States
...and 311 more locations
Local reactions included redness, swelling and pain at the injection site and were recorded by participants in an e-diary. All local reactions were graded based on Center for Biologics Evaluation and Research (CBER) toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure data is reported for any local reaction and any grade.
Time frame: From Day 1 to Day 7 after study vaccination
Percentage of Participants Reporting Any Systemic Events Within 7 Days After Study Vaccination: 18-64 Years
Systemic events (vomiting, diarrhoea, headache, Fatigue/tiredness, chills, new or worsened muscle pain and joint pain) were recorded by participants in an e-diary. All systemic events were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure data is reported for any systemic reaction and any grade.
Time frame: From Day 1 to Day 7 after study vaccination
Percentage of Participants Reporting Any Systemic Events Within 7 Days After Study Vaccination: >=65 Years
Systemic events (vomiting, diarrhoea, headache, Fatigue/tiredness, chills, new or worsened muscle pain and joint pain) were recorded by participants in an e-diary. All systemic events were graded based on CBER toxicity guidelines as Grade 1 (Mild), Grade 2 (Moderate), Grade 3 (Severe) and Grade 4 (potentially life-threatening). In this outcome measure data is reported for any systemic reaction and any grade.
Time frame: From Day 1 to Day 7 after study vaccination
Percentage of Participants Reporting Adverse Events (AEs) From Study Vaccination Through 4 Weeks After Study Vaccination: 18-64 Years
An AE was defined as any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention. Results excluded local reactions and systemic events data.
Time frame: From study vaccination on Day 1 through 4 weeks after study vaccination
Percentage of Participants Reporting AEs From Study Vaccination Through 4 Weeks After Study Vaccination: >=65 Years
An AE was defined as any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention. Results excluded local reactions and systemic events data.
Time frame: From study vaccination on Day 1 through 4 weeks after study vaccination
Percentage of Participants Reporting AEs From Study Vaccination Through 4 Weeks After Study Vaccination: >=18 Years
An AE was defined as any untoward medical occurrence in a participant temporally associated with the use of study intervention, whether or not considered related to the study intervention. Results excluded local reactions and systemic events data.
Time frame: From study vaccination on Day 1 through 4 weeks after study vaccination
Percentage of Participants Reporting Serious Adverse Events (SAEs) From Study Vaccination Through 6 Months After Study Vaccination: 18-64 Years
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria - 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.
Time frame: From Day 1 up to 6 months after vaccination
Percentage of Participants Reporting SAEs From Study Vaccination Through 6 Months After Study Vaccination: >=65 Years
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria - 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.
Time frame: From Day 1 up to 6 months after vaccination
Percentage of Participants Reporting SAEs From Study Vaccination Through 6 Months After Study Vaccination: >=18 Years
An SAE was defined as any untoward medical occurrence that, at any dose, met one or more of the following criteria - 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.
Time frame: From Day 1 up to 6 months after vaccination
Percentage of Participants Reporting First Episode of LCI Cases With Associated Per-Protocol ILI Caused by All Matched Strains at Least 14 Days After Vaccination: 18-64 Years
LCI was defined as influenza infection confirmed through RT-PCR or culture at the central laboratory, unless otherwise specified. Data was obtained during the 2022-2023 northern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 to surveillance cut-off (approximately 6 months)
Percentage of Participants Reporting First Episode of LCI Cases With Associated Per-Protocol ILI Caused by All Matched Strains at Least 14 Days After Vaccination: >=65 Years
LCI was defined as influenza infection confirmed through RT-PCR or culture at the central laboratory, unless otherwise specified. Data was obtained during the 2022-2023 northern and southern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 up to primary surveillance cut-off (approximately 1 year)
Percentage of Participants Reporting First Episode of Culture Confirmed Influenza (CCI) With Associated Per-Protocol ILI Caused by Any Strain at Least 14 Days After Vaccination: 18-64 Years
CCI was defined as influenza infection confirmed through culture at the central laboratory, unless otherwise specified. Per-protocol ILI was defined as occurrence (new onset or worsening of preexisting condition) of at least 1 respiratory symptom concurrently with at least 1 systemic symptom. Data was obtained during the 2022-2023 northern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 to surveillance cut-off (approximately 6 months)
Percentage of Participants Reporting First Episode of CCI With Associated Per-Protocol ILI Caused by Any Strain at Least 14 Days After Vaccination: >=65 Years
CCI was defined as influenza infection confirmed through culture at the central laboratory, unless otherwise specified. Per-protocol ILI was defined as occurrence (new onset or worsening of preexisting condition) of at least 1 respiratory symptom concurrently with at least 1 systemic symptom. Data was obtained during the 2022-2023 northern and southern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 up to primary surveillance cut-off (approximately 1 year)
Percentage of Participants Reporting First Episode of LCI Cases With Associated ILI as Defined by Modified Centers for Disease Control and Prevention (CDC) Caused by Any Strain at Least 14 Days After Vaccination: 18-64 Years
LCI was defined as influenza infection confirmed through RT-PCR or culture at the central laboratory, unless otherwise specified. Data was obtained during the 2022-2023 northern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 to surveillance cut-off (approximately 6 months)
Percentage of Participants Reporting First Episode of LCI Cases With Associated ILI as Defined by Modified CDC Caused by Any Strain at Least 14 Days After Vaccination: >=65 Years
LCI was defined as influenza infection confirmed through RT-PCR or culture at the central laboratory, unless otherwise specified. ILI defined modified CDC: occurrence (new onset or worsening of preexisting condition) of at least 1 of the following respiratory symptoms concurrently with an oral temperature \>37.2 deg C (\>99.0 deg F), sore throat or cough. Data was obtained during the 2022-2023 northern and southern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 up to primary surveillance cut-off (approximately 1 year)
Percentage of Participants Reporting First Episode of LCI Cases With Associated ILI as Defined by World Health Organization (WHO) Caused by Any Strain at Least 14 Days After Vaccination: 18-64 Years
LCI was defined as influenza infection confirmed through RT-PCR or culture at the central laboratory, unless otherwise specified. ILI as per WHO was defined as occurrence (new onset or worsening of preexisting condition) of a cough concurrently with an oral temperature \>=38.0 deg C (\>= 100.4 deg F). Data was obtained during the 2022-2023 northern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 to surveillance cut-off (approximately 6 months)
Percentage of Participants Reporting First Episode of LCI Cases With Associated ILI as Defined by WHO Caused by Any Strain at Least 14 Days After Vaccination: >=65 Years
LCI was defined as influenza infection confirmed through RT-PCR or culture at the central laboratory, unless otherwise specified. ILI as per WHO was defined as occurrence (new onset or worsening of preexisting condition) of a cough concurrently with an oral temperature \>=38.0 deg C (\>= 100.4 deg F). Data was obtained during the 2022-2023 northern and southern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 up to primary surveillance cut-off (approximately 1 year)
Percentage of Participants Reporting First Episode Cases of Influenza as Confirmed by RT-PCR or Local RT-PCR or Culture, With Associated Per-Protocol ILI at Least 14 Days After Vaccination: 18-64 Years
Per-protocol ILI was defined as occurrence (new onset or worsening of preexisting condition) of at least 1 respiratory symptom concurrently with at least 1 systemic symptom. Data was obtained during the 2022-2023 northern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 to surveillance cut-off (approximately 6 months)
Percentage of Participants Reporting First Episode Cases of Influenza as Confirmed by Central RT-PCR or Local RT-PCR or Culture, With Associated Per-Protocol ILI at Least 14 Days After Vaccination: >=65 Years
Per-protocol ILI was defined as occurrence (new onset or worsening of preexisting condition) of at least 1 respiratory symptom concurrently with at least 1 systemic symptom. Data was obtained during the 2022-2023 northern and southern hemisphere influenza season up to surveillance cut-off decided by Sponsor.
Time frame: Day 15 up to primary surveillance cut-off (approximately 1 year)
HAI GMTs Used to Determine GMRs of qIRV to Licensed QIV at 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere- Based on HAI Assay 2: 18-64 Years
Geometric mean titers (GMTs) and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the concentrations and the corresponding CIs (based on the student t distribution) and were reported in the descriptive section. Geometric mean ratios (GMRs) were estimated by the ratio of the GMTs between qIRV recipients compared to licensed QIV recipients vaccine groups and were reported in the statistical analysis section.
Time frame: 4 Weeks after vaccination
HAI GMTs Used to Determine GMRs of qIRV to Licensed QIV for 2022-2023 Northern Hemisphere at 4 Weeks After Vaccination- Based on HAI Assay 2: >=65 Years
GMTs and 2-sided 95% CIs were calculated by exponentiating the mean logarithm of the concentrations and the corresponding CIs (based on the student t distribution) and were reported in the descriptive section. GMRs were estimated by the ratio of the GMTs between qIRV recipients compared to licensed QIV recipients vaccine groups and were reported in the statistical analysis section.
Time frame: 4 Weeks after vaccination
Percentage of Participants and Difference in Percentage of Participants Achieving Seroconversion at 4 Weeks After Vaccination With qIRV and Licensed QIV for 2022-2023 Northern Hemisphere- Based on HAI Assay 2: 18-64 Years
Seroconversion was defined as an HAI titer \<1:10 prior to vaccination and \>=1:40 at the time point of interest, or an HAI titer of \>=1:10 prior to vaccination with a 4-fold rise at the time point of interest. Percentage of participants achieving seroconversion for each strain at 4 weeks after vaccination and exact 2-sided 95% CI is presented in the descriptive section. Difference in percentage of participants (qIRV - QIV) achieving HAI seroconversion for each strain at 4 weeks after vaccination is presented in the statistical analysis section.
Time frame: 4 Weeks after vaccination
Percentage of Participants and Difference in Percentage of Participants Achieving Seroconversion at 4 Weeks After Vaccination With qIRV and Licensed QIV for 2022-2023 Northern Hemisphere- Based on HAI Assay 2: >=65 Years
Seroconversion was defined as an HAI titer \<1:10 prior to vaccination and \>=1:40 at the time point of interest, or an HAI titer of \>=1:10 prior to vaccination with a 4-fold rise at the time point of interest. Percentage of participants achieving seroconversion for each strain at 4 weeks after vaccination and exact 2-sided 95% CI is presented in the descriptive section. Difference in percentage of participants (qIRV - QIV) achieving HAI seroconversion for each strain at 4 weeks after vaccination is presented in the statistical analysis section.
Time frame: 4 Weeks after vaccination
HAI GMTs Used to Determine GMRs of qIRV to Licensed QIV for 2022-2023 Northern Hemisphere at 4 Weeks After Vaccination- Based on HAI Assay 1: 18-64 Years
GMTs and 2-sided 95% CIs were reported in the descriptive section. GMRs were estimated by the ratio of the GMTs between qIRV recipients compared to licensed QIV recipients vaccine groups and were reported in the statistical analysis section.
Time frame: 4 Weeks after vaccination
HAI GMTs Used to Determine GMRs of qIRV to Licensed QIV for 2022-2023 Northern Hemisphere at 4 Weeks After Vaccination - Based on HAI Assay 1: >=65 Years
GMTs and 2-sided 95% CIs were reported in the descriptive section. GMRs were estimated by the ratio of the GMTs between qIRV recipients compared to licensed QIV recipients vaccine groups and were reported in the statistical analysis section.
Time frame: 4 Weeks after vaccination
Percentage of Participants and Difference in Percentage of Participants Achieving Seroconversion at 4 Weeks After Vaccination With qIRV and Licensed QIV for 2022-2023 Northern Hemisphere-Based on HAI Assay 1: 18-64 Years
Seroconversion was defined as an HAI titer \<1:10 prior to vaccination and \>=1:40 at the time point of interest, or an HAI titer of \>=1:10 prior to vaccination with a 4-fold rise at the time point of interest. Percentage of participants achieving seroconversion for each strain at 4 weeks after vaccination and exact 2-sided 95% CI is presented in the descriptive section. Difference in percentage of participants (qIRV - QIV) achieving HAI seroconversion for each strain at 4 weeks after vaccination is presented in the statistical analysis section.
Time frame: 4 Weeks after vaccination
Percentage of Participants and Difference in Percentage of Participants Achieving Seroconversion at 4 Weeks After Vaccination With qIRV and Licensed QIV for 2022-2023 Northern Hemisphere- Based on HAI Assay 1: >=65 Years
Seroconversion was defined as an HAI titer \<1:10 prior to vaccination and \>=1:40 at the time point of interest, or an HAI titer of \>=1:10 prior to vaccination with a 4-fold rise at the time point of interest. Percentage of participants achieving seroconversion for each strain at 4 weeks after vaccination and exact 2-sided 95% CI is presented in the descriptive section. Difference in percentage of participants (qIRV - QIV) achieving HAI seroconversion for each strain at 4 weeks after vaccination is presented in the statistical analysis section.
Time frame: 4 Weeks after vaccination
HAI GMTs at Baseline for the 2022-2023 Northern Hemisphere - Based on HAI Assay 2: 18-64 Years
Time frame: Baseline (Before Vaccination)
HAI GMTs at Baseline for 2022-2023 Northern Hemisphere - Based on HAI Assay 2: >=65 Years
Time frame: Baseline (Before Vaccination)
HAI Geometric Mean Fold Rise (GMFR) From Before Vaccination to 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere- Based on HAI Assay 2: 18-64 Years
GMFRs were defined as ratios of the results after vaccination to the results before vaccination (baseline).
Time frame: Before vaccination (Baseline) to 4 weeks after vaccination
HAI GMFR Before Vaccination to 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere- Based on HAI Assay 2: >=65 Years
GMFRs were defined as ratios of the results after vaccination to the results before vaccination (baseline).
Time frame: Before vaccination (Baseline) to 4 weeks after vaccination
Percentage of Participants With HAI Titers >=1:40 at Baseline and 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere- Based on HAI Assay 2: 18-64 Years
Time frame: Baseline and 4 weeks after vaccination
Percentage of Participants With HAI Titers >=1:40 at Baseline and 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere - Based on HAI Assay 2: >=65 Years
Time frame: Baseline and 4 weeks after vaccination
HAI GMTs at Baseline for 2022-2023 Northern Hemisphere - Based on HAI Assay 1: 18-64 Years
Time frame: Baseline
HAI GMTs at Baseline for 2022-2023 Northern Hemisphere- Based on HAI Assay 1: >=65 Years
Time frame: Baseline
HAI GMFR Before Vaccination to 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere- Based on HAI Assay 1: 18-64 Years
GMFRs were defined as ratios of the results after vaccination to the results before vaccination (baseline).
Time frame: Before vaccination (Baseline) to 4 weeks after vaccination
HAI GMFR Before Vaccination to 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere- Based on HAI Assay 1: >=65 Years
GMFRs were defined as ratios of the results after vaccination to the results before vaccination.
Time frame: Before vaccination (Baseline) to 4 weeks after vaccination
Percentage of Participants With HAI Titers >=1:40 at Baseline and 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere - Based on HAI Assay 1: 18-64 Years
Time frame: Baseline and 4 weeks after vaccination
Percentage of Participants With HAI Titers >=1:40 at Baseline and 4 Weeks After Vaccination for 2022-2023 Northern Hemisphere - Based on HAI Assay 1: >=65 Years
Time frame: Baseline and 4 weeks after vaccination
HAI GMTs at Baseline and 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 2: 18-64 Years
Time frame: Baseline and 4 weeks after vaccination
HAI GMTs at Baseline and 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 2: >=65 Years
Time frame: Baseline and 4 weeks after vaccination
HAI GMFR Before Vaccination to 4 Weeks After Vaccination for 2023 Southern- Based on HAI Assay 2: 18-64 Years
Time frame: Before vaccination (Baseline) to 4 weeks after vaccination
HAI GMFR Before Vaccination to 4 Weeks After Vaccination for 2023 Southern Hemisphere- Based on HAI Assay 2: >=65 Years
GMFRs were defined as ratios of the results after vaccination to the results before vaccination (baseline).
Time frame: Before vaccination (Baseline) to 4 weeks after vaccination
Percentage of Participants Achieving HAI Seroconversion at 4 Weeks After Vaccination for the 2023 Southern Hemisphere - Based on HAI Assay 2: 18-64 Years
Time frame: 4 weeks after vaccination
Percentage of Participants Achieving HAI Seroconversion at 4 Weeks After Vaccination for 2023 Southern Hemisphere- Based on HAI Assay 2: >=65 Years
Seroconversion was defined as an HAI titer \<1:10 prior to vaccination and \>=1:40 at the time point of interest, or an HAI titer of \>=1:10 prior to vaccination with a 4-fold rise at the time point of interest.
Time frame: 4 weeks after vaccination
Percentage of Participants With HAI Titers >=1:40 at Baseline and 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 2: 18-64 Years
Time frame: Baseline and 4 weeks after vaccination
Percentage of Participants With HAI Titers >=1:40 at Baseline and 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 2: >=65 Years
Time frame: Baseline and 4 weeks after vaccination
HAI GMTs at Baseline and 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 1: 18-64 Years
Time frame: Baseline and 4 weeks after vaccination
HAI GMTs at Baseline and 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 1: >=65 Years
Time frame: Baseline and 4 weeks after vaccination
HAI GMFR Before Vaccination to 4 Weeks After Vaccination for 2023 Southern Hemisphere- Based on HAI Assay 1: 18-64 Years
Time frame: Before Vaccination (baseline) to 4 weeks after vaccination
HAI GMFR Before Vaccination to 4 Weeks After Vaccination for the 2023 Southern Hemisphere - Based on HAI Assay 1: >=65 Years
GMFRs were defined as ratios of the results after vaccination to the results before vaccination (baseline).
Time frame: Before vaccination (baseline) to 4 weeks after vaccination
Percentage of Participants Achieving HAI Seroconversion at 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 1: 18-64 Years
Time frame: 4 weeks after vaccination
Percentage of Participants Achieving HAI Seroconversion at 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 1: >=65 Years
Seroconversion was defined as an HAI titer \<1:10 prior to vaccination and \>=1:40 at the time point of interest, or an HAI titer of \>=1:10 prior to vaccination with a 4-fold rise at the time point of interest.
Time frame: 4 weeks after vaccination
Percentage of Participants With HAI Titers >=1:40 at Baseline and 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 1: 18-64 Years
Time frame: Baseline and 4 weeks after vaccination
Percentage of Participants With HAI Titers >=1:40 at Baseline and 4 Weeks After Vaccination for 2023 Southern Hemisphere - Based on HAI Assay 1: >=65 Years
Time frame: Baseline and 4 weeks after vaccination