While the protective role of IgA-producing cells had been well established in combating intestinal pathogens, Iwasaki's lab wondered if triggering IgA response might also produce a localized immune response against respiratory viruses. Working with researchers at Icahn School of Medicine at Mount Sinai in New York, they tested a protein-based vaccine designed to jump-start an IgA immune response, administering it to mice through injections, as is commonly done with systemic immunizations, and also intranasally. They then exposed mice to multiple strains of influenza viruses. They found that mice that had received vaccine intranasally were much better protected against respiratory influenza than those that received injections. Nasal vaccines, but not the shot, also induced antibodies that protected the animals against a variety of flu strains, not just against the strain the vaccine was meant to protect against.