Chikungunya Virus
Conditions
Keywords
chikungunya, virus like particle (VLP), PXVX0317, vaccine, immunogenicity
Brief summary
The purpose of this phase 3, randomized, double-blind, placebo-controlled study is to evaluate the safety and immunogenicity to PXVX0317 in adults ≥65 years of age.
Detailed description
Co-primary Objectives: * To compare the anti-CHIKV serum neutralizing antibody (SNA) response to PXVX0317 and placebo at Day 22, as measured by geometric mean titer (GMT) and clinically relevant difference in seroresponse rate (PXVX0317 minus placebo) in adults ≥65 years of age. * To evaluate the safety of PXVX0317 in adults ≥65 years of age Secondary Objectives: * To compare the anti-CHIKV SNA response to PXVX0317 and placebo at Day 15 and Day 183, as measured by GMT and seroresponse rate. * To compare the anti-CHIKV SNA response to PXVX0317 and placebo in participants ≥65 to \<75 and ≥75 years of age as measured by GMT and seroresponse rate.
Interventions
BIOLOGICALCHIKV VLP/adjuvant
PXVX0317 vaccine is comprised of chikungunya virus virus-like particles (CHIKV VLP), adsorbed on aluminum hydroxide adjuvant
BIOLOGICALPlacebo
Placebo is comprised of formulation buffer
Sponsors
Emergent BioSolutions
Bavarian Nordic
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)
Intervention model description
Participants will be randomized in a 1:1 ratio to receive PXVX0317 or placebo within each age stratum. Participants will be stratified in two age subgroups (≥65 to \<75 and ≥75 years of age). This study will be conducted in the US, using up to 10 sites.
Eligibility
Sex/Gender
ALL
Age
65 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Able and willing to provide informed consent voluntarily signed by participant. Must verbalize understanding of the general procedures of, and reason for the study. * Males or females, ≥65 years of age. * Able to complete all scheduled visits and comply with all study procedures. * Women who are not of childbearing potential (CBP): surgically sterile (at least six weeks post bilateral tubal ligation, bilateral oophorectomy or hysterectomy); or postmenopausal (defined as a history of ≥12 consecutive months without menses prior to randomization in the absence of other pathologic or physiologic causes, following cessation of exogenous post menopausal sex-hormonal treatment). * Participants must be in stable health in the opinion of the investigator for at least 30 days prior to screening (eg, no hospital admission for acute illness in the last 30 days prior to screening).
Exclusion criteria
* Participation or planned participation in an investigational clinical trial (eg, vaccine, drug, medical device, or medical procedure) within 30 days of Day 1 and for the duration of the study. Note: Participation in an observational trial or follow-up phase of a trial may be allowed; however, these instances should be discussed with the sponsor's medical monitor (MM) prior to enrollment. * Prior receipt of any CHIKV vaccine. * Positive laboratory evidence of current infection with human immunodeficiency virus (HIV), hepatitis C virus (HCV) or hepatitis B virus (HBV). * Body mass index (BMI) ≥35 kg/m\^2 * History of any known or suspected allergy or history of anaphylaxis to any component of the investigational product (IP). * History of any known congenital or acquired immunodeficiency or immunosuppressive condition that could impact response to vaccination (eg, leukemia, lymphoma, malignancy, functional or anatomic asplenia, alcoholic cirrhosis). Note: History of basal cell and squamous cell carcinoma of the skin or carcinoma in situ of the cervix considered cured would not be exclusionary. History of a malignancy considered cured from over five years from the date of screening with minimal risk of recurrence is not exclusionary. * Prior or anticipated use of systemic immunomodulatory or immunosuppressive medications from six months prior to screening through Day 22. Note: Systemic corticosteroid use at a dose or equivalent dose of 20 mg of prednisone daily for 14 days or more within 90 days of screening through Day 22 is exclusionary. The use of inhaled, intranasal, topical, or ocular steroids is allowed. * Bleeding disorder or receipt of anticoagulants in the 21 days prior to screening, contraindicating intramuscular (IM) vaccination, as judged by the investigator. * Moderate or severe acute illness with or without fever (oral temperature ≥100.4°F or 38.0°C). * Receipt or anticipated receipt of immunoglobulin from 180 days prior to screening through Day 22. * Medical condition (such as dementia) that, in the opinion of the investigator, could adversely impact the participant's participation in or conduct of the study. * Evidence of substance abuse that, in the opinion of the investigator, could adversely impact the participant's participation in or conduct of the study. * Identified as an investigator or employee of an Investigator or study center with direct involvement in the proposed study, or identified as an immediate family member (ie, parent, spouse) of the investigator or employee with direct involvement in the proposed study. * Receipt or anticipated receipt of any vaccine from 30 days prior to Day 1 through Day 22. * Receipt or anticipated receipt of blood or blood-derived products from 90 days prior to screening through Day 22. * Any planned elective surgery that may interfere with study participation or conduct. * Any other medical condition that, in the opinion of the investigator, could adversely impact the participant's participation in or conduct of the study.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Incidence of Adverse Events of Special Interest (AESI) | 182 days postvaccination | Incidence of AESIs, through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population). |
| Incidence of Solicited Adverse Events (AE) | 7 days postvaccination | Incidence of solicited AEs through Day 8 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population). |
| Incidence of Unsolicited AEs | 28 days postvaccination | Incidence of unsolicited AEs through Day 29 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population). |
| Incidence of Serious Adverse Events (SAE) | 182 days postvaccination | Incidence of SAEs through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population). |
| Incidence of Medically Attended Adverse Events (MAAE) | 182 days postvaccination | Incidence of MAAEs through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population). |
| Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Day 22 in Baseline Seronegative Participants | 21 days postvaccination | Difference in anti-CHIKV SNA titer (NT80) seroresponse rate (PXVX0317 minus placebo) and associated 95 percent confidence interval (CI) at Day 22. |
| Anti-CHIKV SNA Titer (NT80) Geometric Mean Titers (GMT) at Day 22 | 21 days postvaccination | Anti-CHIKV SNA titer (NT80) GMT and associated 95 percent CIs at Day 22 for PXVX0317 and placebo. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Anti-CHIKV SNA GMTs at Days 15 and 183 | Day 15, and 183 (14 and 182 days postvaccination, respectively) | Anti-CHIKV SNA GMTs with associated 95 percent CIs at Day 15, and Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for the IEP, all age strata combined. |
| Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) | Day 15, 22, and 183 (14, 21 and 182 days postvaccination, respectively) | Geometric mean fold increase (GMFI) in anti-CHIKV SNA titers from Day 1 to Day 15, Day 22, and Day 183 for the IEP for all age strata combined. |
| Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | Day 15, 22 and 183 (14, 21 and 182 days postvaccination, respectively) | Number and percentage of participants with anti-CHIKV SNA titers ≥15 and 4-fold rise over baseline at Day 15, Day 22, and Day 183 for the IEP for all age strata combined. |
| Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Days 15 and 183 | Day 15 and 183 (14 and 182 days postvaccination, respectively) | Difference in anti-CHIKV SNA titer (NT80) seroresponse rate (PXVX0317 minus placebo) with associated 95 percent CIs at Day 15 and Day 183. |
Countries
United States
Participant flow
Recruitment details
This was a multicenter study conducted in the United States, using 10 sites. Healthy adult participants ≥65 year of age were enrolled in this study. Recruitment Period was from May 12, 2022 to December 02, 2022.
Participants by arm
| Arm | Count |
|---|---|
| Group 1 - PXVX0317 PXVX0317 vaccine is comprised of chikungunya virus virus-like particles (CHIKV VLP), adsorbed on aluminum hydroxide adjuvant | 206 |
| Group 2 - Placebo Placebo is comprised of formulation buffer | 207 |
| Total | 413 |
Withdrawals & dropouts
| Period | Reason | FG000 | FG001 |
|---|---|---|---|
| Overall Study | Death | 1 | 1 |
| Overall Study | Lost to Follow-up | 3 | 8 |
| Overall Study | Withdrawal by Subject | 2 | 10 |
Baseline characteristics
| Characteristic | Group 2 - Placebo | Total | Group 1 - PXVX0317 |
|---|---|---|---|
| Age, Continuous | 71 years STANDARD_DEVIATION 4.5 | 71 years STANDARD_DEVIATION 4.9 | 71 years STANDARD_DEVIATION 5.3 |
| Baseline Anti-CHIKV SNA Serostatus Missing | 1 Participants | 1 Participants | 0 Participants |
| Baseline Anti-CHIKV SNA Serostatus Negative (<LLOQ) | 196 Participants | 397 Participants | 201 Participants |
| Baseline Anti-CHIKV SNA Serostatus Positive (≥LLOQ) | 10 Participants | 15 Participants | 5 Participants |
| Body Mass Index (BMI) | 27.6 kg/m^2 STANDARD_DEVIATION 3.9 | 27.5 kg/m^2 STANDARD_DEVIATION 3.94 | 27.3 kg/m^2 STANDARD_DEVIATION 3.98 |
| Ethnicity (NIH/OMB) Hispanic or Latino | 90 Participants | 183 Participants | 93 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 116 Participants | 228 Participants | 112 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 1 Participants | 2 Participants | 1 Participants |
| Height | 167.1 cm STANDARD_DEVIATION 9.84 | 166.8 cm STANDARD_DEVIATION 9.63 | 166.4 cm STANDARD_DEVIATION 9.42 |
| Race (NIH/OMB) American Indian or Alaska Native | 1 Participants | 2 Participants | 1 Participants |
| Race (NIH/OMB) Asian | 1 Participants | 5 Participants | 4 Participants |
| Race (NIH/OMB) Black or African American | 29 Participants | 49 Participants | 20 Participants |
| Race (NIH/OMB) More than one race | 5 Participants | 9 Participants | 4 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 3 Participants | 4 Participants | 1 Participants |
| Race (NIH/OMB) White | 168 Participants | 344 Participants | 176 Participants |
| Sex: Female, Male Female | 117 Participants | 242 Participants | 125 Participants |
| Sex: Female, Male Male | 90 Participants | 171 Participants | 81 Participants |
| Weight | 77.2 kg STANDARD_DEVIATION 13.29 | 76.5 kg STANDARD_DEVIATION 13.45 | 75.8 kg STANDARD_DEVIATION 13.61 |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk |
|---|---|---|
| deaths Total, all-cause mortality | 1 / 206 | 1 / 207 |
| other Total, other adverse events | 46 / 206 | 44 / 207 |
| serious Total, serious adverse events | 4 / 206 | 3 / 207 |
Outcome results
Primary
Anti-CHIKV SNA Titer (NT80) Geometric Mean Titers (GMT) at Day 22
Anti-CHIKV SNA titer (NT80) GMT and associated 95 percent CIs at Day 22 for PXVX0317 and placebo.
Time frame: 21 days postvaccination
Population: Immunogenicity evaluable population (all randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV human SNA assay sample within the analysis window (Day 19 through 27, inclusive), had no measurable anti-CHIKV human SNA assay titer at Day 1 (i.e., seronegative at baseline; participants missing a Day 1 titer were excluded from IEP), and had no important exclusionary protocol deviation or other reason for exclusion as defined prior to unblinding).
| Arm | Measure | Value (GEOMETRIC_MEAN) |
|---|---|---|
| Group 1 - PXVX0317 | Anti-CHIKV SNA Titer (NT80) Geometric Mean Titers (GMT) at Day 22 | 724 Titer |
| Group 2 - Placebo | Anti-CHIKV SNA Titer (NT80) Geometric Mean Titers (GMT) at Day 22 | 8 Titer |
Comparison: Day 22p-value: <0.000195% CI: [69, 117]ANOVA
Primary
Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Day 22 in Baseline Seronegative Participants
Difference in anti-CHIKV SNA titer (NT80) seroresponse rate (PXVX0317 minus placebo) and associated 95 percent confidence interval (CI) at Day 22.
Time frame: 21 days postvaccination
Population: Immunogenicity Evaluable Population (IEP): All participants in the modified intent-to-treat (mITT) population who provide evaluable serum sample results for Day 22 within the required time frame of Day 19 through Day 27, inclusive; have no measurable anti-CHIKV SNA at Day 1; and have no important protocol deviation or other reason to be excluded as defined prior to unblinding. IEP is the primary population for all immunogenicity analyses.
| Arm | Measure | Value (NUMBER) |
|---|---|---|
| Group 1 - PXVX0317 | Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Day 22 in Baseline Seronegative Participants | 87.3 percentage of participants |
| Group 2 - Placebo | Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Day 22 in Baseline Seronegative Participants | 1.1 percentage of participants |
Comparison: Day 22p-value: <0.000195% CI: [80, 90.3]Chi-squared
Primary
Incidence of Adverse Events of Special Interest (AESI)
Incidence of AESIs, through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).
Time frame: 182 days postvaccination
Population: Safety population (vaccinated participants who provided safety assessment data), All ages pooled.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Group 1 - PXVX0317 | Incidence of Adverse Events of Special Interest (AESI) | 0 Participants |
| Group 2 - Placebo | Incidence of Adverse Events of Special Interest (AESI) | 1 Participants |
Primary
Incidence of Medically Attended Adverse Events (MAAE)
Incidence of MAAEs through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).
Time frame: 182 days postvaccination
Population: Safety population (vaccinated participants who provided safety assessment data), All ages pooled.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Group 1 - PXVX0317 | Incidence of Medically Attended Adverse Events (MAAE) | 19 Participants |
| Group 2 - Placebo | Incidence of Medically Attended Adverse Events (MAAE) | 23 Participants |
Primary
Incidence of Serious Adverse Events (SAE)
Incidence of SAEs through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).
Time frame: 182 days postvaccination
Population: Safety population (vaccinated participants who provided safety assessment data), All ages pooled.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Group 1 - PXVX0317 | Incidence of Serious Adverse Events (SAE) | 4 Participants |
| Group 2 - Placebo | Incidence of Serious Adverse Events (SAE) | 3 Participants |
Primary
Incidence of Solicited Adverse Events (AE)
Incidence of solicited AEs through Day 8 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).
Time frame: 7 days postvaccination
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Group 1 - PXVX0317 | Incidence of Solicited Adverse Events (AE) | 25 Participants |
| Group 2 - Placebo | Incidence of Solicited Adverse Events (AE) | 28 Participants |
Primary
Incidence of Unsolicited AEs
Incidence of unsolicited AEs through Day 29 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).
Time frame: 28 days postvaccination
Population: Safety population (vaccinated participants who provided safety assessment data), All ages pooled.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Group 1 - PXVX0317 | Incidence of Unsolicited AEs | 26 Participants |
| Group 2 - Placebo | Incidence of Unsolicited AEs | 34 Participants |
Secondary
Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI)
Geometric mean fold increase (GMFI) in anti-CHIKV SNA titers from Day 1 to Day 15, Day 22, and Day 183 for the IEP for all age strata combined.
Time frame: Day 15, 22, and 183 (14, 21 and 182 days postvaccination, respectively)
Population: Immunogenicity evaluable population (all randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV human SNA assay sample within the analysis window, had no measurable anti-CHIKV human SNA assay titer at Day 1, and had no important protocol deviation deemed exclusionary or other reason to be excluded as defined prior to unblinding).~Number analyzed is number of participants with a sample result available at both Day 1 and the indicated visit.
| Arm | Measure | Group | Value (GEOMETRIC_MEAN) |
|---|---|---|---|
| Group 1 - PXVX0317 | Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) | Day 15 | 48.5 Fold increase in Anti-CHIKV SNA titre |
| Group 1 - PXVX0317 | Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) | Day 22 | 93.9 Fold increase in Anti-CHIKV SNA titre |
| Group 1 - PXVX0317 | Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) | Day 183 | 29.3 Fold increase in Anti-CHIKV SNA titre |
| Group 2 - Placebo | Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) | Day 15 | 1.2 Fold increase in Anti-CHIKV SNA titre |
| Group 2 - Placebo | Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) | Day 22 | 1.1 Fold increase in Anti-CHIKV SNA titre |
| Group 2 - Placebo | Anti-CHIKV SNA Geometric Mean Fold Increase (GMFI) | Day 183 | 1.0 Fold increase in Anti-CHIKV SNA titre |
Comparison: Day 15p-value: <0.0001t-test, 2 sided
Comparison: Day 22p-value: <0.0001t-test, 2 sided
Comparison: Day 183p-value: <0.0001t-test, 2 sided
Secondary
Anti-CHIKV SNA GMTs at Days 15 and 183
Anti-CHIKV SNA GMTs with associated 95 percent CIs at Day 15, and Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for the IEP, all age strata combined.
Time frame: Day 15, and 183 (14 and 182 days postvaccination, respectively)
Population: Immunogenicity evaluable population (all randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV human SNA assay sample within the analysis window, had no measurable anti-CHIKV human SNA assay titer at Day 1, and had no important protocol deviation deemed exclusionary or other reason to be excluded as defined prior to unblinding).~Number analyzed is number of participants with a sample result available at the indicated visit.
| Arm | Measure | Group | Value (GEOMETRIC_MEAN) |
|---|---|---|---|
| Group 1 - PXVX0317 | Anti-CHIKV SNA GMTs at Days 15 and 183 | Day 15 | 378 Titer |
| Group 1 - PXVX0317 | Anti-CHIKV SNA GMTs at Days 15 and 183 | Day 183 | 233 Titer |
| Group 2 - Placebo | Anti-CHIKV SNA GMTs at Days 15 and 183 | Day 15 | 9 Titer |
| Group 2 - Placebo | Anti-CHIKV SNA GMTs at Days 15 and 183 | Day 183 | 8 Titer |
Comparison: Day 15p-value: <0.000195% CI: [32, 56]ANOVA
Comparison: Day 183p-value: <0.000195% CI: [22, 35]ANOVA
Secondary
Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Days 15 and 183
Difference in anti-CHIKV SNA titer (NT80) seroresponse rate (PXVX0317 minus placebo) with associated 95 percent CIs at Day 15 and Day 183.
Time frame: Day 15 and 183 (14 and 182 days postvaccination, respectively)
Population: Immunogenicity evaluable population (all randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV human SNA assay sample within the analysis window, had no measurable anti-CHIKV human SNA assay titer at Day 1, and had no important protocol deviation deemed exclusionary or other reason to be excluded as defined prior to unblinding).~Number analyzed is number of participants with a sample result available at the indicated visit.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Group 1 - PXVX0317 | Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Days 15 and 183 | Day 15 | 82.3 percentage of participants |
| Group 1 - PXVX0317 | Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Days 15 and 183 | Day 183 | 75.5 percentage of participants |
| Group 2 - Placebo | Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Days 15 and 183 | Day 15 | 2.8 percentage of participants |
| Group 2 - Placebo | Anti-CHIKV SNA Titer (NT80) Seroresponse Rates at Days 15 and 183 | Day 183 | 1.2 percentage of participants |
Comparison: Day 15p-value: <0.000195% CI: [72.3, 84.6]Chi-squared
Comparison: Day 183p-value: <0.000195% CI: [67.1, 80.1]Chi-squared
Secondary
Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline
Number and percentage of participants with anti-CHIKV SNA titers ≥15 and 4-fold rise over baseline at Day 15, Day 22, and Day 183 for the IEP for all age strata combined.
Time frame: Day 15, 22 and 183 (14, 21 and 182 days postvaccination, respectively)
Population: Immunogenicity evaluable population (all randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV human SNA assay sample within the analysis window, had no measurable anti-CHIKV human SNA assay titer at Day 1, and had no important protocol deviation deemed exclusionary or other reason to be excluded as defined prior to unblinding).~Number analyzed is number of participants with a sample result available at the indicated visit.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Group 1 - PXVX0317 | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | SNA titers ≥ 15 at Day 15 | 94.5 percentage of participants |
| Group 1 - PXVX0317 | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | SNA titers ≥ 15 at Day 22 | 95.2 percentage of participants |
| Group 1 - PXVX0317 | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | SNA titers ≥ 15 at Day 183 | 92.9 percentage of participants |
| Group 1 - PXVX0317 | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | ≥4-fold rise over baseline at Day 15 | 85.6 percentage of participants |
| Group 1 - PXVX0317 | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | ≥4-fold rise over baseline at Day 22 | 89.4 percentage of participants |
| Group 1 - PXVX0317 | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | ≥4-fold rise over baseline at Day 183 | 83.2 percentage of participants |
| Group 2 - Placebo | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | ≥4-fold rise over baseline at Day 22 | 1.1 percentage of participants |
| Group 2 - Placebo | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | SNA titers ≥ 15 at Day 15 | 2.8 percentage of participants |
| Group 2 - Placebo | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | ≥4-fold rise over baseline at Day 15 | 2.8 percentage of participants |
| Group 2 - Placebo | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | SNA titers ≥ 15 at Day 22 | 1.1 percentage of participants |
| Group 2 - Placebo | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | ≥4-fold rise over baseline at Day 183 | 1.2 percentage of participants |
| Group 2 - Placebo | Subjects With Anti-CHIKV SNA Titer ≥15 and 4-fold Rise Over Baseline | SNA titers ≥ 15 at Day 183 | 1.2 percentage of participants |
Comparison: SNA titers ≥15 at Day 15p-value: <0.000195% CI: [86, 94.6]Chi-squared
Comparison: SNA titers ≥15 at Day 22p-value: <0.000195% CI: [89.2, 96.5]Chi-squared
Comparison: SNA titers ≥15 at Day 183p-value: <0.000195% CI: [86.3, 94.8]Chi-squared
Comparison: ≥4-fold rise over baseline at Day 15p-value: <0.000195% CI: [75.9, 87.5]Chi-squared
Comparison: ≥4-fold rise over baseline at Day 22p-value: <0.000195% CI: [82.4, 92]Chi-squared
Comparison: ≥4-fold rise over baseline at Day 183p-value: <0.000195% CI: [75.2, 86.8]Chi-squared