Chunguang Yang, Tianchi Luo, Yanpei Li, Zhuo Chen, Zhengshi Lin, Fengxue Zhang, Yang Wang, Weiqi Pan, Jingwei Liu, Changyuan Kang, Nan Ma, Jun Yang, Wenlu Wang, Zifeng Yang
Airborne transmission plays a central role in the spread of seasonal influenza; however, the determinants governing strain-specific airborne infectivity remain poorly understood. Here, we integrated exposure-infection assays with controlled bioaerosol chamber experiments to quantitatively resolve differences between influenza A and B viruses across aerosolization and aging processes. By coupling these measurements with an effective inhaled dose model, we enabled strain-resolved comparisons of exposure potential as a function of host age and activity level. Our results show that strain-dependent differences in aerosolization efficiency, hygroscopic behavior, virion morphology, and physical stability cannot fully account for variations in airborne infectivity. Instead, biological inactivation during aerosol aging emerges as a key factor governing the loss of infectivity in airborne particles. Accordingly, A/H3N2 maintains higher aerosol-phase infectivity across size ranges, whereas influenza B strains display more rapid loss of infectivity. Collectively, these findings identify aerosol-phase biological stability as a primary determinant of strain-specific airborne infectivity and provide a quantitative framework for assessing the aerosol exposure potential of emerging influenza variants and informing indoor respiratory health interventions.