Airborne Virus Shedding of Respiratory Syncytial Virus Compared to Influenza A Virus in Hospitalized Patients

Airborne transmission is an important route for the spread of respiratory viruses. To assess the potential for airborne shedding of influenza A virus (IAV) and respiratory syncytial virus (RSV), this study compared the presence of viral RNA in air samples collected near hospitalized patients. Patients with IAV or RSV infection and a nasopharyngeal swab cycle threshold value of 28 or lower were included. Air sampling was performed using a vacuum cleaner equipped with a detachable soluble air filter attached to the hose inlet. For each patient, one sample was collected 50 cm dorsally and one 50 cm ventrally relative to the patient's face, each for 2 min. Filters were dissolved and analyzed for viral RNA by RT-qPCR. In total, 59 patients were included: 39 with IAV infection and 21 with RSV infection, including one patient co-infected with both viruses. Air samples were more frequently positive in RSV-infected patients than in IAV-infected patients (12/21 [57%] vs. 6/39 [15%], p = 0.0012). In multivariable analysis, RSV-infections remained associated with higher rates of air sample positivity after adjustment for nasopharyngeal viral load. These findings suggest different aerosol shedding between RSV and IAV, although differences in infectious potential remain to be determined. © 2026 The Author(s). Journal of Medical Virology published by Wiley Periodicals LLC.