COVID-19, SARS-CoV-2, Omicron variant, BA.2.12.1, BA.4, BA.5 sublineages, immune imprinting, vaccine, neutralizing antibody, hybrid immunity
Phase-1, intranasal, DelNS1-nCoV-RBD LAIV, COVID-19
COVID-19 vaccine, SARS-CoV-2, Omicron variant, mucosal immunity, saliva, IgA