The study demonstrated that a combination of intramuscular PD1-based receptor-binding domain (RBD) DNA vaccine (PD1-RBD-DNA) prime and intranasal live attenuated influenza-based vaccine (LAIV-HK68-RBD) boost vaccination regimen induced the strongest mucosal broadly neutralising antibodies and lung resident memory CD8 T cells, which prevented live SARS-CoV-2 nasal challenges in two animal models
