Researchers led by the Fisabio Foundation found that dermcidin, a natural antimicrobial peptide present in sweat and respiratory tissues, can block influenza infection by binding to a highly conserved region of the viral hemagglutinin protein and preventing cell entry. The study also found that people who did not develop flu-like symptoms had markedly higher baseline dermcidin levels, suggesting the molecule may help reduce susceptibility to infection and could support the development of broader-spectrum antivirals.