Incidence of solicited AEs through Day 8 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).

The number of participants assessed is the number of safety population participants who completed a memory aid following the vaccination.

Incidence of unsolicited AEs through Day 29 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).

Safety population (vaccinated participants who provided safety assessment data), All ages pooled

Incidence of AESIs, through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).

Safety population (vaccinated participants who provided safety assessment data), All ages pooled

Incidence of MAAEs through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).

Safety population (vaccinated participants who provided safety assessment data), All ages pooled

Incidence of SAEs through Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for all age strata combined (safety population).

Safety population (vaccinated participants who provided safety assessment data), All ages pooled

Anti-CHIKV SNA seroresponse rates for PXVX0317 (CHIKV VLP vaccine) and placebo, difference (PXVX0317 minus placebo), and associated 95% confidence interval (CI) at Day 22 for the immunogenicity evaluable population (IEP), all age strata combined.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding). Groups 1, 2, and 3 are combined, as participants received same treatment of PXVX0317 (dose, adjuvant, schedule), with only difference being the lot of manufactured vaccine. Data is reported for PXVX0317 vaccinated vs. placebo.

Anti-CHIKV SNA seroresponse rates and associated 95% confidence interval for PXVX0317 (CHIKV VLP vaccine) and placebo at Day 22 for the immunogenicity evaluable population (IEP), all age strata combined.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding).

Anti-CHIKV SNA GMTs and associated 95% CIs at Day 22 for PXVX0317 (CHIKV VLP vaccine) and placebo for the IEP, all age strata combined.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding). Groups 1, 2, and 3 are combined, as participants received same treatment of PXVX0317 (dose, adjuvant, schedule), with only difference being the lot of manufactured vaccine. Data is reported for PXVX0317 vaccinated vs. placebo.

Anti-CHIKV SNA GMTs and associated 95% CIs at Day 22 for PXVX0317 (CHIKV VLP vaccine) and placebo for the IEP, all age strata combined.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding).

Anti-CHIKV SNA GMTs and associated 95% CIs between all three pairs of PXVX0317 (CHIKV VLP vaccine) lots (104:105, 104:106, 105:106) in adults 18 to <46 years of age in the IEP at Day 22. Placebo group 4 is not relevant for this lot-to-lot consistency analysis.

Reported GMT estimates and 95% CIs are derived from an ANOVA model that includes site and product lot as fixed effects assuming normality of log titers.

Adults 18 to <46 years in Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding). Placebo group 4 does not apply for this PXVX0317 lot-to-lot consistency analysis.

Anti-CHIKV SNA GMTs and associated 95% CIs for PXVX0317 (CHIKV VLP vaccine) and placebo in adults 18 to <46 years of age in the IEP at Day 22.

Adults 18 to <46 years in Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding).

Anti-CHIKV SNA seroresponse rates for PXVX0317 (CHIKV VLP vaccine) and placebo, difference (PXVX0317 minus placebo), and associated 95% CIs at Day 15, Day 183, and Day 8, in that order, for the IEP, all age strata combined.

Number analyzed is number of participants with a sample result available at the indicated visit.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding). Groups 1, 2, and 3 are combined, as participants received same treatment of PXVX0317 (dose, adjuvant, schedule), with only difference being the lot of manufactured vaccine. Data is reported for PXVX0317 vaccinated vs. placebo.

Anti-CHIKV SNA seroresponse rates and associated 95% CIs for PXVX0317 (CHIKV VLP vaccine) and placebo at Day 15, Day 183, and Day 8, in that order, for the IEP, all age strata combined.

Number analyzed is number of participants with a sample result available at the indicated visit.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding).

Anti-CHIKV SNA GMTs with associated 95% CIs at Day 8, Day 15, and Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for the IEP, all age strata combined.

Number analyzed is number of participants with a sample result available at the indicated visit.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding). Groups 1, 2, and 3 are combined, as participants received same treatment of PXVX0317 (dose, adjuvant, schedule), with only difference being the lot of manufactured vaccine. Data is reported for PXVX0317 vaccinated vs. placebo.

Anti-CHIKV SNA GMTs with associated 95% CIs at Day 8, Day 15, and Day 183 for PXVX0317 (CHIKV VLP vaccine) and placebo for the IEP, all age strata combined.

Number analyzed is number of participants with a sample result available at the indicated visit

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding).

Geometric mean fold increase (GMFI) in anti-CHIKV SNA titers from Day 1 to Day 8, Day 15, Day 22, and Day 183 for the IEP for all age strata combined.

Fold rise in geometric mean titer is the ratio of the post-baseline value to the baseline value (e.g. number of 2 represents a post-baseline doubling of geometric mean titer).

Number analyzed is number of participants with a sample result available at both Day 1 and the indicated visit.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding). Groups 1, 2, and 3 are combined, as participants received same treatment of PXVX0317 (dose, adjuvant, schedule), with only difference being the lot of manufactured vaccine. Data is reported for PXVX0317 vaccinated vs. placebo.

Geometric mean fold increase (GMFI) in anti-CHIKV SNA titers from Day 1 to Day 8, Day 15, Day 22, and Day 183 for the IEP for all age strata combined.

Fold rise in geometric mean titer is the ratio of the post-baseline value to the baseline value (e.g. number of 2 represents a post-baseline doubling of geometric mean titer).

Number analyzed is number of participants with a sample result available at both Day 1 and the indicated visit.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding).

Number and percentage of participants with anti-CHIKV SNA titers ≥15 and 4-fold rise over baseline at Day 8, Day 15, Day 22, and Day 183 for the IEP for all age strata combined.

Number analyzed is number of participants with a sample result available at the indicated visit.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding). Groups 1, 2, and 3 are combined, as participants received same treatment of PXVX0317 (dose, adjuvant, schedule), with only difference being the lot of manufactured vaccine. Data is reported for PXVX0317 vaccinated vs. placebo.

Number and percentage of participants with anti-CHIKV SNA titers ≥15 and 4-fold rise over baseline at Day 8, Day 15, Day 22, and Day 183 for the IEP for all age strata combined.

Number analyzed is number of participants with a sample result available at the indicated visit.

Immunogenicity evaluable population (randomized and vaccinated participants who provided an evaluable Day 22 anti-CHIKV SNA sample within the analysis window, had no measurable anti-CHIKV SNA titer at Day 1, and had no reason to be excluded as defined prior to unblinding).