Ad5, human serotype 5 adenovirus; Ad26, human serotype 26 adenovirus; ChAd, chimpanzee adenovirus; IM, intramuscular; ID, intradermal; IN, intranasal RBD, receptor- binding domain; SARS- CoV-2, severe acute respiratory syndrome coronavirus 2; LNP, lipid nanoparticle; NHP, non-Human Primates; ADE, antibody-dependent enhancement