GMT ratio of GMT SCB-2019 over GMT Comirnaty on Day 15;GMT ratio of GMT SCB-2019 over GMT CoronaVac Vaccine on Day 15;GMT ratio of GMT SCB-2019 over GMT COVID-19 Vaccine Janssen on Day 15;Local and systemic solicited AEs reported within 7 days after study vaccination;SAEs, AEs leading to early termination from the study, MAAEs, and AESIs;Unsolicited AEs reported from Visit 1 (Day 1) through Safety Call Day 29

GMT ratio of GMT SCB-2019 over GMT Comirnaty on Day 15;GMT ratio of GMT SCB-2019 over GMT CoronaVac Vaccine on Day 15;GMT ratio of GMT SCB-2019 over GMT COVID-19 Vaccine Janssen on Day 15;Local and systemic solicited AEs reported within 7 days after study vaccination;SAEs, AEs leading to early termination from the study, MAAEs, and AESIs;Unsolicited AEs reported from Visit 1 (Day 1) through Safety Call Day 29

Geometric Mean Titer (GMT) ratio of GMT booster over GMT primary series;Local and systemic solicited AEs reported within 7 days after study vaccination;SAEs, AEs leading to early termination from the study, MAAEs, and AESIs;SCR difference: Seroconversion Rate (SCR) booster minus SCR primary series;;Unsolicited AEs reported from Visit 1 (Day 1) through Safety Call Day 43

Geometric Mean Titer (GMT) ratio of GMT booster over GMT primary series;Local and systemic solicited AEs reported within 7 days after study vaccination;SAEs, AEs leading to early termination from the study, MAAEs, and AESIs;SCR difference: Seroconversion Rate (SCR) booster minus SCR primary series;;Unsolicited AEs reported from Visit 1 (Day 1) through Safety Call Day 43

To assess the safety and reactogenicity of SCB-2019 vaccine given as a booster dose after primary vaccination series with one of the selected authorized or investigational COVID-19 vaccines or SCB-2019 vaccine.;To demonstrate that SCB-2019 vaccine when given as a homologous booster dose elicits an immune response that is non-inferior to the immune response when given as primary 2-dose series, as measured by Virus Neutralization Assay (VNA).

To assess the safety and reactogenicity of SCB-2019 vaccine given as a booster dose after primary vaccination series with one of the selected authorized or investigational COVID-19 vaccines or SCB-2019 vaccine.;To demonstrate that SCB-2019 vaccine when given as a homologous booster dose elicits an immune response that is non-inferior to the immune response when given as primary 2-dose series, as measured by Virus Neutralization Assay (VNA).