A new pre-pathogen strategy aims to bridge the gap before specific respiratory vaccines are available. Researchers reported in Science Advances that the K3-SPG vaccine adjuvant temporarily primes innate immunity in mice, offering measurable protection against influenza A virus and SARS-CoV-2 without prior exposure. The nanosized adjuvant combines CpG oligodeoxynucleotide (TLR9 agonism) with schizophyllan, linking trained-immunity mechanisms to respiratory defense.