Viable viruses in airborne particles detected during cough by participants with acute respiratory viral infections

Aim: This study aimed to evaluate the survival of airborne viruses in exhaled particles produced during voluntary coughing by participants infected with respiratory viruses. Methods: We utilized a novel technique, recruiting patients with diverse respiratory infections and performing real-time polymerase chain reaction (rt-PCR) and culture analyses. Respiratory particles were aged in an airborne state to reach equilibrium with ambient relative humidity following cough in 13 participants who presented to hospital with PCR-positive respiratory viral infections. Findings: Nasopharyngeal swab rt-PCR identified the following single infections; five influenza A virus (IAV), three respiratory syncytial virus (RSV), one rhinovirus, one parainfluenza virus (PIV)-3, and one PIV-4. Two co-infections were identified: one RSV/IAV and one RSV/human coronavirus HCoV-HKU1. Virus was identified by rt-PCR in cough particles collected from nine of 13 (69%) participants, with viable virus recovered from seven of 13 (54%) participants (IAV (one), RSV (four), PIV-3 (one), HCoV-HKU1 (one)). RSV-infected participants shed more respiratory particles than influenza participants, with a median of 1.07 × 10⁴ ± 19.9 × 10³ particles/L (P=0.044). Conclusion: Our study demonstrates the detection of diverse and viable respiratory viruses, including new insights of PIV and RSV infection in aged cough particles, and highlights the risk of transmission through the air.