Vaccine(87) SARS-CoV-2(69) COVID-19 vaccine(46) Vaccines(45) COVID-19(40) vaccination(37) elicited(31) Efficacy(31) dose(30) neutralizing antibody(30) induce(26) the SARS-CoV-2(24) mice(24) pandemic(23) viral infection(22) immune response(21) COVID-19 pandemic(21) virus(21) PROTECT(21) expressing(21) antibody(20) immunization(20) RBD(20) Infection(20) effective(20) Protein(19) humoral(18) robust(17) clinical trial(16) demonstrated(15)