Cell-mediated response for both Th1 and Th2 (e.g. INF-γ, IL-4 using Enzyme-linked ImmunoSpot (ELISpot) or other system) - Stage 2;GMFR of IgG antibody to the SARS-CoV-2 RBD from baseline measured by ELISA - Stage 2;GMFR of neutralizing antibody to the SARS-CoV-2 from baseline measured by pseudovirus and wild-type virus neutralization assays - Stage 2;GMT of IgG antibody to the SARS-CoV-2 RBD measured by Enzyme-linked Immunosorbent Assay (ELISA) - Stage 2;GMT of neutralizing antibody to the SARS-CoV-2 measured by pseudovirus and wild-type virus neutralization assays - Stage 2;Occurrence of immediate systemic reactions - Stage 1;Occurrence of Serious Adverse Events (SAEs), Medically Attended Adverse Events (MAAEs) and Adverse Events of Special Interest (AESIs) during the whole study period - Stage 1;Occurrence of solicited local Adverse Events (AEs) during 7 days post each vaccination - Stage 1;Occurrence of solicited systemic AEs during 7 days post each vaccination - Stage 1;Occurrence of unsolicited AEs during 28 days post each vaccination - Stage 1;(Only in Sentinel group) Occurrence of out-of-normal range clinical laboratory test results (including change from baseline values) during 7 days post 1st vaccination - Stage 1;Percentage of participants with ≥ 4-fold rise from baseline in ELISA IgG titer - Stage 2;Percentage of participants with ≥ 4-fold rise from baseline in pseudovirus and wild-type neutralizing antibody titer - Stage 2

Cell-mediated response for both Th1 and Th2 (e.g. INF-γ, IL-4 using Enzyme-linked ImmunoSpot (ELISpot) or other system) - Stage 2;GMFR of IgG antibody to the SARS-CoV-2 RBD from baseline measured by ELISA - Stage 2;GMFR of neutralizing antibody to the SARS-CoV-2 from baseline measured by pseudovirus and wild-type virus neutralization assays - Stage 2;GMT of IgG antibody to the SARS-CoV-2 RBD measured by Enzyme-linked Immunosorbent Assay (ELISA) - Stage 2;GMT of neutralizing antibody to the SARS-CoV-2 measured by pseudovirus and wild-type virus neutralization assays - Stage 2;Occurrence of immediate systemic reactions - Stage 1;Occurrence of Serious Adverse Events (SAEs), Medically Attended Adverse Events (MAAEs) and Adverse Events of Special Interest (AESIs) during the whole study period - Stage 1;Occurrence of solicited local Adverse Events (AEs) during 7 days post each vaccination - Stage 1;Occurrence of solicited systemic AEs during 7 days post each vaccination - Stage 1;Occurrence of unsolicited AEs during 28 days post each vaccination - Stage 1;(Only in Sentinel group) Occurrence of out-of-normal range clinical laboratory test results (including change from baseline values) during 7 days post 1st vaccination - Stage 1;Percentage of participants with ≥ 4-fold rise from baseline in ELISA IgG titer - Stage 2;Percentage of participants with ≥ 4-fold rise from baseline in pseudovirus and wild-type neutralizing antibody titer - Stage 2