Comparative GMT (Geometric Mean Titer) of neutralizing antibody to SARS-CoV-2 between the Test Group and Placebo Group, measured by wild-type virus neutralization assay at 2 weeks post heterologous booster vaccination;GMFR (Geometric Mean Fold Rise) of neutralizing antibody to SARS-CoV-2 from baseline measured by wild-type virus neutralization assay at each time point post heterologous booster vaccination;GMFR (Geometric Mean Fold Rise) of SARS-CoV-2 RBD-binding antibody from baseline measured by ECLIA at each time point post heterologous booster vaccination;GMT (Geometric Mean Titer) of neutralizing antibody to SARS-CoV-2 measured by wild-type virus neutralization assay at each time point post heterologous booster vaccination;GMT (Geometric Mean Titer) of SARS-CoV-2 RBD-binding antibody measured by ECLIA at each time point post heterologous booster vaccination;(Only applicable to CMI analysis set) Cell-mediated immunity assessment using IFN-γ ELISpot at each time point post heterologous booster vaccination;Percentage of participants with ≥4-fold rise from baseline in neutralizing antibody to SARS-CoV-2 measured by wild-type virus neutralization assay at each time point post heterologous booster vaccination;Percentage of participants with ≥4-fold rise from baseline in SARS-CoV-2 RBD-binding antibody measured by ECLIA at each time point post heterologous booster vaccination

Comparative GMT (Geometric Mean Titer) of neutralizing antibody to SARS-CoV-2 between the Test Group and Placebo Group, measured by wild-type virus neutralization assay at 2 weeks post heterologous booster vaccination;GMFR (Geometric Mean Fold Rise) of neutralizing antibody to SARS-CoV-2 from baseline measured by wild-type virus neutralization assay at each time point post heterologous booster vaccination;GMFR (Geometric Mean Fold Rise) of SARS-CoV-2 RBD-binding antibody from baseline measured by ECLIA at each time point post heterologous booster vaccination;GMT (Geometric Mean Titer) of neutralizing antibody to SARS-CoV-2 measured by wild-type virus neutralization assay at each time point post heterologous booster vaccination;GMT (Geometric Mean Titer) of SARS-CoV-2 RBD-binding antibody measured by ECLIA at each time point post heterologous booster vaccination;(Only applicable to CMI analysis set) Cell-mediated immunity assessment using IFN-γ ELISpot at each time point post heterologous booster vaccination;Percentage of participants with ≥4-fold rise from baseline in neutralizing antibody to SARS-CoV-2 measured by wild-type virus neutralization assay at each time point post heterologous booster vaccination;Percentage of participants with ≥4-fold rise from baseline in SARS-CoV-2 RBD-binding antibody measured by ECLIA at each time point post heterologous booster vaccination