By Hugo Francisco de Souza Reviewed by Lauren Hardaker Feb 4 2026 A rare human challenge-style trial shows that even with poor ventilation and prolonged exposure, influenza may fail to spread unless viral shedding, host susceptibility, and air dynamics align just right. Study: Evaluating modes of influenza transmission (EMIT-2): Insights from lack of transmission in a controlled transmission trial with naturally infected donors . Image credit: Pixel-Shot/Shutterstock.com In a recent study