SARS-CoV-2(1) antibody(1) omicron(1) breath(1) Neutralizing antibody titer(1) neutralizing antibody titers(1) addition(1) clinical trial(1) variant(1) Inactivated vaccine(1) inactivated(1) Safe(1) PROTECT(1) Vaccine(1) VoC(1) virus(1) vaccine candidate(1) dose(1) prototype(1) induce(1) Inactivated Vaccines(1) Delta(1) immune responses(1) BBIBP-CorV(1) Support(1) virus(1) immune response(1) Genetic(1) stability(1) Omicron variant(1)