Efficacy of a Plant-derived Quadrivalent Virus-like Particle (VLP) Vaccine in the Elderly

Study Overview
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Brief Summary
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This Phase 3 study was intended to assess the relative efficacy of the Quadrivalent VLP Influenza Vaccine during the 2018-2019 influenza season compared to a licensed vaccine in elderly adults 65 years of age and older. One dose of VLP Influenza Vaccine (30 μg/strain) or of Comparator (15 μg/strain) was to be administered to 12,738 participants.

Detailed Description
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This randomized, observer-blind, active-controlled multicenter, Phase 3 study was conducted at multiple sites. The composition of the Quadrivalent VLP Influenza Vaccine used in this study included a mix of recombinant H1, H3, and two B hemagglutinin proteins expressed as VLPs for the 2018-2019 influenza virus strains. A total of 12,794 healthy male and female participants aged 65 years and older were randomized in a 1:1 ratio into one of two parallel treatment groups, such that 6,396 participants were randomized to receive the Quadrivalent VLP Influenza Vaccine at a dose of 30 μg/strain and 6,398 participants were randomized to receive the comparator. Within the two treatment groups, participants were stratified by site and two age groups (65-74 years of age and 75 years of age and older in a 2:1 ratio). Participants participated in this study for approximately nine months, during which a first visit was scheduled on Day 0 for screening and vaccine administration.

Official Title
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A Randomized, Observer-blind, Active Comparator-controlled, Multicenter, Phase 3 Study to Assess the Efficacy, Safety, and Immunogenicity of a Plant-derived Quadrivalent VLP Influenza Vaccine in Adults 65 Years of Age and Older

Conditions
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Virus Diseases, RNA Virus Infections, Respiratory Tract Diseases, Respiratory Tract Infections

Intervention / Treatment
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* Biological: Quadrivalent VLP Vaccine
* Biological: Fluarix Quadrivalent® Comparator Vaccine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants must have read, understood, and signed the informed consent form (ICF) prior to participating in the study; participants must also complete study-related procedures and communicate with the study staff at visits and by phone during the study; Participants must have a body mass index (BMI) ≤35 kg/m^2; Participants are considered by the Investigator to be reliable and likely to cooperate with the assessment procedures and be available for the duration of the study; Male and female participants must be 65 years of age and older at the Screening/Vaccination visit (Visit 1); Participants must be non-institutionalized (e.g. not living in rehabilitation centres or old-age homes; living in an elderly community is acceptable) and have no acute or evolving medical problems prior to study participation and no clinically relevant abnormalities that could jeopardize participant safety or interfere with study assessments, as assessed by the Principal Investigator or sub-Investigator (thereafter referred as Investigator) and determined by medical history, physical examination, and vital signs; Note: Participants with a pre-existing chronic disease are allowed to participate if the disease is stable and, according to the Investigator's judgment, the condition is unlikely to confound the results of the study or pose additional risk to the participant by participating in the study. Stable disease is generally defined as no new onset or exacerbation of pre-existing chronic disease three months prior to vaccination. Based on the Investigator's judgment, a participant with more recent stabilization of a disease could also be eligible. Exclusion Criteria: According to the Investigator's opinion, history of an ongoing acute or evolving medical or neuropsychiatric illness. 'Evolving' was defined as: Requiring a new medical or surgical treatment during the three months prior to study vaccine administration unless the criteria outlined in inclusion criterion no. 5 can be met (i.e. the Investigator can justify inclusion based upon the innocuous nature of medical/surgical events and/or treatments); Requiring any significant change in a chronic medication (i.e. drug, dose, frequency) during the three months prior to study vaccine administration due to uncontrolled symptoms or drug toxicity unless the innocuous nature of the medication change meets the criteria outlined in inclusion criterion no. 5 and is appropriately justified by the Investigator. Any medical or neuropsychiatric condition or any history of excessive alcohol use or drug abuse that would render the participant unable to provide informed consent or unable to provide valid safety observations and reporting, including methadone (methadone as treatment for opioid dependence may be acceptable if the participant has been otherwise opioid-free for at least three years); Any autoimmune disease other than hypothyroidism on stable replacement therapy (including, but not limited to rheumatoid arthritis, systemic lupus erythematosus, Crohn's disease, type 1 diabetes, and inflammatory bowel disease) or any confirmed or suspected immunosuppressive condition or immunodeficiency including known or suspected human immunodeficiency virus (HIV), Hepatitis B or C infection, the presence of lymphoproliferative disease; Any history of status asthmaticus or ongoing serious problems with asthma, hospitalization for asthma control, or recurrent asthma episodes requiring medical attention in the last three years (one or more episodes per year); Administration or planned administration of any non-influenza vaccine within 30 days prior to randomization up to blood sampling on Day 21. Immunization on an emergency basis was evaluated case-by-case by the Investigator; Administration of any adjuvanted or investigational influenza vaccine within one year prior to randomization or planned administration prior to the completion of the study; Administration of any 'standard', non-adjuvanted influenza vaccine (e.g. live attenuated trivalent/quadrivalent inactivated influenza vaccine or split trivalent/quadrivalent inactivated influenza vaccine administered by intranasal, intradermal, or IM route) within six months prior to randomization and up to completion of the study; Use of any investigational or non-registered product within 30 days or five half-lives, whichever is longer, prior to randomization or planned use during the study period. Participants may not participate in any other investigational or marketed drug study while participating in this study until after the study; Treatment with systemic glucocorticoids at a dose exceeding 10 mg of prednisone (or equivalent) per day for more than seven consecutive days or for ten or more days in total, within one month of study vaccine administration; any other cytotoxic or immunosuppressant drug, or any immunoglobulin preparation within three months of vaccination and until the completion of the study. Low doses of nasal or inhaled glucocorticoids are allowed. Topical steroids are permitted; Any significant disorder of coagulation including, but not limited to, treatment with warfarin derivatives or heparin. Persons receiving prophylactic anti-platelet medications (e.g. low-dose aspirin [no more than 100 mg/day]), and without a clinically apparent bleeding tendency are eligible. Participants treated with new generation drugs that do not increase the risk of IM bleeding (e.g. clopidogrel) are also eligible; History of allergy to any of the constituents of the Quadrivalent VLP Influenza Vaccine, any components of the active comparator quadrivalent vaccine, or tobacco; History of anaphylactic allergic reactions to plants or plants components (including fruits and nuts); Use of antihistamines within 48 hours prior to study vaccination; Daily use of large doses of medication for pain control or inflammation (e.g. opioids, nonsteroidal anti-inflammatory drugs [NSAIDs]). Use of a singular regular dose either in the morning or at bedtime would not be exclusionary; Use of prophylactic medications (e.g. acetaminophen/paracetamol, aspirin, naproxen, or ibuprofen) within 24 hours of randomization to prevent or pre-empt symptoms due to vaccination; Planned use of influenza antiviral treatment medication before the collection of nasopharyngeal (NP) swabs (e.g. oseltamivir, zanamivir, rapivab); Have a rash, dermatological condition, tattoos, muscle mass, or any other abnormalities at the injection site that may interfere with injection site reaction rating; Participants who have received a blood transfusion within 90 days prior to study vaccination; Participants with abnormal vital signs (systolic blood pressure [BP] ≥ 150 mmHg and/or diastolic BP ≥ 95 mmHg for individuals taking antihypertensive medication and ≥ 140 mmHg and/or diastolic BP ≥ 90 mmHg for individuals not taking antihypertensive medication; heart rate [HR] ≤ 45 beats/min and ≥ 100 beats/min) evaluated by an Investigator to be clinically significant. A participant with abnormal vital signs results may be included in the study based on Investigator's judgment (e.g. a resting HR ≤ 45 in highly trained athletes); Presence of any febrile illness (including an oral temperature [OT] ≥ 38.0 ˚C within 24 hours prior to vaccination; Cancer or treatment for cancer within three years prior to study vaccine administration. Persons with a history of cancer who are disease-free without treatment for three years or more are eligible. However, individuals with conditions such as treated and uncomplicated basal cell carcinoma of the skin or non-treated, non-disseminated local prostate cancer may be eligible; Participants identified as an Investigator or employee of the Investigator or clinical site with direct involvement in the proposed study, or identified as an immediate family member (i.e. parent, spouse) of the Investigator or any employee of Medicago (or their family members); Participants with a history of Guillain-Barré Syndrome.

Ages Eligible for Study
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Minimum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: This is a randomized, observer-blind, active comparator-controlled, multicenter, Phase 3 efficacy study.
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Quadrivalent VLP Vaccine<br>Participants received one intramuscular (IM) injection of 0.5 mL of 30 μg/strain of the Quadrivalent VLP Influenza Vaccine on Day 0. | Biological: Quadrivalent VLP Vaccine<br>* Single dose of a 30 µg/strain of Quadrivalent VLP Vaccine<br>|
| Active Comparator: Fluarix Quadrivalent® Comparator Vaccine<br>Participants received one IM injection of 0.5 mL of 15 μg/strain of the Fluarix Quadrivalent® comparator vaccine on Day 0. | Biological: Fluarix Quadrivalent® Comparator Vaccine<br>* Single dose of a 15 μg/strain of Fluarix Quadrivalent® Comparator Vaccine<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Occurrences of Protocol-Defined Influenza-Like Illness (ILI) Due to Any Laboratory-Confirmed Influenza Strains | Occurrences of laboratory-confirmed ILI caused by any influenza viral strains was measured by reverse transcriptase polymerase chain reaction (RT-PCR). A participant was considered to have protocol-defined ILI if the participant met at least one of the following pre-defined respiratory symptoms: sore throat, cough, sputum production, wheezing, or difficulty breathing and at least one of the following systemic symptoms: fever (defined as a temperature > 37.2 °C or > 99.0 °F), chills, tiredness, headache or myalgia. The number of laboratory-confirmed ILI cases caused by any influenza strains are reported. | Day 14 (post-vaccination) up to  9 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Occurrences of Laboratory Confirmed Protocol-Defined Influenza-Like Illness (ILI) Caused by Vaccine-Matched Influenza Strains | Occurrences of protocol-defined ILI due to laboratory-confirmed influenza caused by influenza viral types/subtypes that were matched (and/or antigenically similar) to the strains covered in the vaccine formulation was measured by sequential RT-PCR & serotyping. The vaccine-matched strains included: homologous A/Michigan/45/2015 [H1N1], homologous A/Singapore/INFIMH-16-0019/2016 [H3N2], homologous B/Colorado/06/2017 and homologous B/Phuket/3073/2013) covered in the vaccine formulation. A participant was considered to have protocol-defined ILI if the participant met at least one of the following pre-defined respiratory symptoms: sore throat, cough, sputum production, wheezing, or difficulty breathing and at least one of the following systemic symptoms: fever (defined as a temperature > 37.2 °C or > 99.0 °F), chills, tiredness, headache or myalgia. The number of laboratory-confirmed ILI cases caused by vaccine-matched influenza strains (all matched strains) are reported. | Day 14 (post-vaccination) up to  9 months | 
| Number of Occurrences of Protocol-Defined Respiratory Illness Due to Any Laboratory-Confirmed Influenza Strains | Occurrences of protocol-defined respiratory illness due to laboratory-confirmed influenza strain (matched, mismatched, and un-typed) was measured by sequential RT-PCR. A protocol-defined respiratory illness was determined by the occurrence of at least 1 of the following respiratory symptoms: sneezing, stuffy nose, sore throat, cough, sputum production, wheezing, or difficulty breathing. The number of protocol-defined respiratory illness cases caused by any laboratory-confirmed influenza strain (matched, mismatched, and un-typed) are reported. | Day 14 (post-vaccination) up to  9 months | 
| Number of Occurrences of Protocol-Defined Respiratory Illness Vaccine Caused by Vaccine-Matched Influenza Strains | Occurrences of protocol-defined respiratory illness vaccine caused by vaccine-matched influenza strains was measured by sequential RT-PCR & serotyping. The vaccine-matched strains included: homologous A/Michigan/45/2015 [H1N1], homologous A/Singapore/INFIMH-16-0019/2016 [H3N2], homologous B/Colorado/06/2017 and homologous B/Phuket/3073/2013. The protocol-defined respiratory illness was determined by the occurrence of at least 1 of the following respiratory symptoms: sneezing, stuffy nose, sore throat, cough, sputum production, wheezing, or difficulty breathing. The number of protocol-defined respiratory illness cases caused by one or more vaccine-matched strains are reported. | Day 14 (post-vaccination) up to  9 months | 
| Number of Occurrences of Protocol-Defined ILI | Occurrences of protocol-defined ILI that were confirmed or not by laboratory testing were assessed. A participant was considered to have protocol-defined ILI if the participant met at least one of the following pre-defined respiratory symptoms: sore throat, cough, sputum production, wheezing, or difficulty breathing and at least one of the following systemic symptoms: fever (defined as a temperature > 37.2 °C or > 99.0 °F), chills, tiredness, headache or myalgia. The number of protocol-defined ILI cases (confirmed or not) are reported. | Day 14 (post-vaccination) up to  9 months | 
| Number of Participants With at Least One Immediate Complaints | Immediate complaints were defined as any solicited local or systemic reactions. Solicited local reactions included: erythema, swelling, and pain at the injection site) and solicited systemic reactions included: fever, headache, fatigue, muscle aches, joint aches, chills, a feeling of general discomfort, swelling in the axilla, and swelling in the neck. | 15 minutes post vaccination | 
| Number of Participants With at Least One Solicited Local and Systemic Reactions | Participants were monitored for both solicited local reactions (erythema, swelling, and pain at the injection site) and solicited systemic reactions (fever, headache, fatigue, muscle aches, joint aches, chills, a feeling of general discomfort, swelling in the axilla, and swelling in the neck) from the time of vaccination through Day 7. Any solicited local or systemic immediate complaint was also included. | Day 0 (post-vaccination) to Day 7 | 
| Number of Participants With ≥ Severe Solicited Local and Systemic Reaction | Participants were monitored for both solicited local reactions (erythema, swelling, and pain at the injection site) and solicited systemic reactions (fever, headache, fatigue, muscle aches, joint aches, chills, a feeling of general discomfort, swelling in the axilla, and swelling in the neck). The intensity of the solicited reactions was graded as mild (1)-easily tolerated and does not interfere with usual activity; moderate (2)-interferes with daily activity, but the participant is still able to function; severe (3)-incapacitating and the participant is unable to work or complete usual activity or potentially life threatening; (4)-likely to be life-threatening if not treated in a timely manner, according to the Food and Drug Administration (FDA) Guidance for Industry. ≥ Severe events included severe and potentially life-threatening events. Any ≥severe solicited reactions are reported. | Day 0 (post-vaccination) to Day 7 | 
| Number of Participants With ≥ Severe Related Solicited Reactions | Participants were monitored for both solicited local reactions (erythema, swelling, & pain at the injection site) & solicited systemic reactions (fever, headache, fatigue, muscle aches, joint aches, chills, a feeling of general discomfort, swelling in axilla, & swelling in neck). The intensity of solicited reactions was graded as mild (1)-easily tolerated and does not interfere with usual activity; moderate (2)-interferes with daily activity, but the participant is still able to function; severe (3)-incapacitating and the participant is unable to work or complete usual activity or potentially life threatening; (4)-likely to be life-threatening if not treated in a timely manner, according to the FDA Guidance for Industry. ≥ Severe events included severe and potentially life-threatening events. Any ≥severe related (possibly related, probably related, and definitely related to the study treatments [as defined by investigator]) solicited events are reported. | Day 0 (post-vaccination) to Day 7 | 
| Number of Participants With Unsolicited Treatment-Emergent Adverse Events (TEAEs) | Participants were monitored for unsolicited TEAEs (e.g., nasopharyngitis, upper respiratory tract infection, headache, and pain). An adverse event (AE) or adverse experience was defined as any untoward medical occurrence in a participant or clinical investigation participant who received study drug, with or without a causal relationship with the treatment. An AE was considered treatment-emergent if it began on or after the date and time of Study Day 0 vaccination. | Day 0 (post-vaccination) to Day 21 | 
| Number of Participants With ≥ Severe Unsolicited TEAEs | Participants were monitored for unsolicited TEAEs (e.g., nasopharyngitis, upper respiratory tract infection, headache, and pain). AE: any untoward medical occurrence in a participant or clinical investigation participant who received study drug, with or without a causal relationship with the treatment. An AE was considered treatment-emergent if it began on or after the date and time of Study Day 0 vaccination. The intensity of the solicited reactions was graded as mild (1)-easily tolerated and does not interfere with usual activity; moderate (2)-interferes with daily activity, but the participant is still able to function; severe (3)-incapacitating and the participant is unable to work or complete usual activity or potentially life threatening; (4)-likely to be life-threatening if not treated in a timely manner, according to the FDA Guidance for Industry. ≥ severe events included severe and potentially life-threatening events. Any ≥ severe unsolicited reactions are reported. | Day 0 (post-vaccination) to Day 21 | 
| Number of Participants With ≥ Severe Related Unsolicited Reactions | Participants were monitored for unsolicited TEAEs (e.g., nasopharyngitis, upper respiratory tract infection, headache, & pain). AE: any untoward medical occurrence in a participant who received study drug, with or without a causal relationship with treatment. An AE was considered treatment-emergent if it began on or after date & time of Study Day 0 vaccination. Intensity of solicited reactions was graded as mild (1) easily tolerated & not interfere with usual activity; moderate (2) interferes with daily activity, but participant still able to function; severe (3) incapacitating & participant unable to work/complete usual activity/ potentially life threatening; (4) likely to be life-threatening if not treated in a timely manner, according to FDA Guidance for Industry. ≥ severe events included severe & potentially life-threatening events. Any ≥severe related (possibly, probably, & definitely related to study treatments [as defined by investigator]) unsolicited events are reported. | Day 0 (post-vaccination) to Day 21 | 
| Number of Participants With at Least One Serious Adverse Event (SAE) | An AE was any untoward medical occurrence in a participant who received study drug, with or without a causal relationship with treatment. An SAE was an AE that resulted in death, was life threatening, resulted in a persistent or significant disability or incapacity, resulted in or prolonged an existing hospitalization, was a congenital anomaly or birth defect, or was another important medical event. | Day 0 to  9 months | 
| Number of Occurrences of Death | The number of participants who died during the study was assessed. | Day 0 up to  9 months | 
| Number of Participants Who Withdrew Due to an AE | An AE or adverse experience was defined as any untoward medical occurrence in a participant or clinical investigation participant who received study drug, with or without a causal relationship with the treatment. An AE can be any favorable and unintended sign, symptom, or disease temporally associated with the use of a medicinal product, whether or not related to a medicinal product. | Day 0 up to  9 months | 
| Number of Participants With at Least One New Onset Chronic Diseases (NOCDs) | All NOCDs that may plausibly have an allergic, autoimmune or inflammatory component were reported. Plausibility should be interpreted broadly however; the only clear exceptions were degenerative conditions such as osteoarthritis, age-related physiologic changes and life-style diseases. In this context, most cancers, cardiac conditions and kidney diseases should be reported. NOCDs were collected from vaccination on Day 0 to the end of the surveillance period. | Day 0 up to  9 months | 
| Geometric Mean Titers (GMTs) of Hemagglutination Inhibition (HI) Antibody Response for Each Homologous and Heterologous Influenza Strain | GMTs were measured using a HI assay for the homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013, and the heterologous strains: H1N1 = A/Brisbane/59/2007; H3N2 = A/Uruguay/716/2007; B/Malaysia = B/Malaysia/2506/2004; B/Florida = B/Florida/4/2006. | Baseline (Day 0), Day 21 | 
| Percentage of Participants With Seroconversion Measured by HI Antibody Response for Each Homologous and Heterologous Strain | The percentage of participants in a given treatment group with either a ≥ 4-fold increase in reciprocal HI titers between Day 0 and Day 21 or a rise of undetectable HI titer (i.e. < 10) pre-vaccination (Day 0) to an HI titer of ≥ 40 on Day 21 was measured using an HI assay for the homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013, and the heterologous strains: H1N1 = A/Brisbane/59/2007; H3N2 = A/Uruguay/716/2007; B/Malaysia = B/Malaysia/2506/2004; B/Florida = B/Florida/4/2006. | Day 0 (pre-vaccination) to Day 21 | 
| Percentage of Participants With Seroprotection Measured by HI Antibody Response for Each Homologous and Heterologous Strain | The percentage of participants in a given treatment group attaining a reciprocal HI titer of ≥ 40 on Day 21 (the percentage of vaccine recipients with a serum HI titer of at least 1:40 following vaccination) was measured using an HI assay for homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013, and the heterologous strains: H1N1 = A/Brisbane/59/2007; H3N2 = A/Uruguay/716/2007; B/Malaysia = B/Malaysia/2506/2004; B/Florida = B/Florida/4/2006. | Baseline (Day 0), Day 21 | 
| Geometric Mean Fold Rise (GMFR) of HI Antibody Response for Each Homologous and Heterologous Strain | GMFR, the geometric mean of the ratio of GMTs (Day 21/Day 0), was measured using an HI assay homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013, and the heterologous strains: H1N1 = A/Brisbane/59/2007; H3N2 = A/Uruguay/716/2007; B/Malaysia = B/Malaysia/2506/2004; B/Florida = B/Florida/4/2006. | Baseline (Day 0), Day 21 | 
| GMTs of Microneutralization (MN) Antibody Response for Each Homologous Strain | GMTs were measured using an MN assay for homologous strains:H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013. | Baseline (Day 0), Day 21 | 
| Percentage of Participants With Seroconversion Measured by MN Antibody Response for Each Homologous Strain | The percentage of participants in a given treatment group with either a ≥ 4-fold increase in reciprocal MN titers between Day 0 and Day 21 or a rise of undetectable MN titer (i.e. 7.1) pre-vaccination (Day 0) to an MN titer of ≥ 28.3 at Day 21 post-vaccination were measured using an MN assay for homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013. | Day 0 (pre-vaccination) to Day 21 | 
| GMFR of MN Antibody Response for Each Homologous Strain | GMFR, the geometric mean of the ratio of GMTs (Day 21/Day 0), was measured using an MN assay for H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013. | Baseline (Day 0), Day 21 | 
| Geometric Mean Areas (GMA) of Single Radial Hemolysis (SRH) Antibody Response for Each Homologous Strain | GMA was measured using an SRH assay for homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013. | Baseline (Day 0), Day 21 | 
| Percentage of Participants With Seroconversion Measured by SRH Antibody Response for Each Homologous Strain | The percentage of participants in a given treatment group showing at least 50 % increase in GMA between Days 0 and 21 were measured using an SRH assay for homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013. | Day 0 (pre-vaccination) to Day 21 | 
| Percentage of Participants With Seroprotection Measured by SRH Antibody Response for Each Homologous Strain | The percentage of participants in a given treatment group attaining an area ≥ 25 mm^2 following vaccination (Day 21) were measured using an SRH assay for homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013. | Baseline (Day 0), Day 21 | 
| GMFR of SRH Antibody Response for Each Homologous Strain | GMFR, the geometric mean of the ratio of GMTs (Day 21/Day 0), was measured using an SRH assay for homologous strains: H1N1 = A/Michigan/45/2015; H3N2 = A/Singapore/INFIMH-16-0019/2016; B/Colorado = B/Colorado/06/2017; B/Phuket = B/Phuket/3073/2013. | Baseline (Day 0), Day 21 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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efficacy, plant-made, virus-like particle, hemagglutinin, vaccine, safety