Efficasy: Geometric mean fold rise (GMFR) of neutralizing antibody titer against SARS-CoV-2 in blood after 4 weeks (Day 29) of treatment with the study drugSafety: Specific adverse events (injection site and systemic) and adverse reactions; unspecified adverse events and adverse reactions; serious adverse events and adverse reactions; laboratory data; 12-lead ECG (dose escalation part only)

Efficasy: Geometric mean fold rise (GMFR) of neutralizing antibody titer against SARS-CoV-2 in blood after 4 weeks (Day 29) of treatment with the study drugSafety: Specific adverse events (injection site and systemic) and adverse reactions; unspecified adverse events and adverse reactions; serious adverse events and adverse reactions; laboratory data; 12-lead ECG (dose escalation part only)