One nasal dose kept mice protected against flu and COVID for 100 days

Professor Ken Ishii's team at the University of Tokyo wondered whether the body's fast, non-specific first-responder defenses could be trained to stand guard before any vaccine exists. In mice, a single nasal dose of an immune adjuvant called K3-SPG helped the animals survive influenza with less weight loss and resist SARS-CoV-2 — with protection still detectable 100 days later, far stronger than injections under the skin or into the bloodstream. Rather than wiping out the virus, the treatment seemed to help the body tolerate infection and limit lung damage. Published in Science Advances; human safety and effectiveness remain untested.