This is a randomized, double-blinded, placebo-controlled study to evaluate the safety and immunogenicity of DelNS1-2019-nCoV-RBD-OPT1 as booster vaccine for COVID-19 in healthy adults who have received 2 doses of BNT162b2. Each subject will receive 2 vaccinations or matching placebo 3 weeks apart.
To evaluate the safety and immunogenicity of DelNS1-2019-nCoV-RBD-OPT1 as booster vaccine for COVID-19 in healthy adults who have received 2 doses of BNT162b2