* individuals with fever \>37.5°c (axillary), or any acute illness at baseline (day 1) or within 3 days prior to randomization; * individuals with laboratory-confirmed sars-cov-2 infection at visit 1 (determined by positive rapid antigen test or rt-pcr); * individuals who have received an investigational or licensed covid-19 vaccine prior to day 1 (except for primary series with comirnaty, vaxzevria, coronavac vaccines, or primary and booster dose of coronavac), or plan to receive covid-19 vaccine during the study period; * individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines; * individuals who have received any other investigational product within 30 days prior to day 1 or intend to participate in another clinical study at any time during the conduct of this study.

* individuals with fever \>37.5°c (axillary), or any acute illness at baseline (day 1) or within 3 days prior to randomization; * individuals with laboratory-confirmed sars-cov-2 infection at visit 1 (determined by positive rapid antigen test or rt-pcr); * individuals who have received an investigational or licensed covid-19 vaccine prior to day 1 (except for primary series with comirnaty, vaxzevria, coronavac vaccines, or primary and booster dose of coronavac), or plan to receive covid-19 vaccine during the study period; * individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines; * individuals who have received any other investigational product within 30 days prior to day 1 or intend to participate in another clinical study at any time during the conduct of this study.

individuals with fever >37.5°c (axillary), or any acute illness at baseline (day 1) or within 3 days prior to randomization; individuals with laboratory-confirmed sars-cov-2 infection at visit 1 (determined by positive rapid antigen test or rt-pcr); individuals who have received an investigational or licensed covid-19 vaccine prior to day 1 (except for primary series with comirnaty, vaxzevria, coronavac vaccines, or primary and booster dose of coronavac), or plan to receive covid-19 vaccine during the study period; individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines; individuals who have received any other investigational product within 30 days prior to day 1 or intend to participate in another clinical study at any time during the conduct of this study.

individuals with fever >37.5°c (axillary), or any acute illness at baseline (day 1) or within 3 days prior to randomization; individuals with laboratory-confirmed sars-cov-2 infection at visit 1 (determined by positive rapid antigen test or rt-pcr); individuals who have received an investigational or licensed covid-19 vaccine prior to day 1 (except for primary series with comirnaty, vaxzevria, coronavac vaccines, or primary and booster dose of coronavac), or plan to receive covid-19 vaccine during the study period; individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines; individuals who have received any other investigational product within 30 days prior to day 1 or intend to participate in another clinical study at any time during the conduct of this study.

individuals with fever >37.5°c (axillary), or any acute illness at baseline (day 1) or within 3 days prior to randomization; individuals with laboratory-confirmed sars-cov-2 infection at visit 1 (determined by positive rapid antigen test or rt-pcr); individuals who have received an investigational or licensed covid-19 vaccine prior to day 1 (except for primary series with comirnaty, covid-19 vaccine janssen, or coronavac vaccines or with scb-2019 vaccine as part of clo-scb-2019-003 study), or plan to receive covid-19 vaccine during the study period; individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines; individuals who have received any other investigational product within 30 days prior to day 1 or intend to participate in another clinical study at any time during the conduct of this study.

individuals with fever >37.5°c (axillary), or any acute illness at baseline (day 1) or within 3 days prior to randomization; individuals with laboratory-confirmed sars-cov-2 infection at visit 1 (determined by positive rapid antigen test or rt-pcr); individuals who have received an investigational or licensed covid-19 vaccine prior to day 1 (except for primary series with comirnaty, covid-19 vaccine janssen, or coronavac vaccines or with scb-2019 vaccine as part of clo-scb-2019-003 study), or plan to receive covid-19 vaccine during the study period; individuals who have a history of severe adverse reaction associated with a vaccine or severe allergic reaction (e.g., anaphylaxis) to any component of the study vaccines; individuals who have received any other investigational product within 30 days prior to day 1 or intend to participate in another clinical study at any time during the conduct of this study.