Albumin was chosen as a carrier as it is actively transported across the mucosal barrier by FcRn, a receptor found on mucosal epithelial cells.

Upon intranasal delivery to several different mouse strains, the albumin-antigen fusion vaccines induced both systemic and mucosal antigen-specific antibody responses. The mice were found to be protected against challenge with SARS-CoV-2 and influenza A. Adjuvant was included and could also be site-specifically conjugated to the albumin carrier.

Importantly, when the new albumin-based vaccine strategy was benchmarked against an intramuscularly administered mRNA vaccine or an intranasally administered alternative where an antigen was fused to a carrier of similar size as albumin, only the albumin-based intranasal vaccine gave rise to robust mucosal IgA antibody responses.