Controlled human influenza infection reveals heterogeneous expulsion of infectious virus into air.

Summary

Using a novel sampling tunnel, investigators directly captured and quantified infectious influenza virus expelled into air from experimentally infected humans. Expelled infectious loads varied by orders of magnitude across individuals and correlated with infectious viral loads in saliva/nasopharynx and with symptoms, with expelled aerosols maintaining viral diversity.

Key Findings

• A modular influenza sampling tunnel enabled culture-based quantification and sequencing of infectious virus from exhaled particles.
• Expelled infectious virus loads varied over three orders of magnitude among individuals.
• Emission magnitude correlated with infectious viral loads in saliva and nasopharyngeal swabs and with clinical symptoms.
• Expelled aerosols preserved viral diversity similar to that detected in clinical samples.

Clinical Implications

Infection control may need to account for high-emitters and symptom-linked peaks, supporting targeted masking, ventilation, and testing strategies during periods of high contagiousness.

Limitations

• Generalizability from controlled challenge settings to community transmission is uncertain.
• Detailed sample size and demographic breadth were not provided in the abstract.

Future Directions

Identify host and behavioral determinants of high emission, assess intervention impact (masking, ventilation) on infectious emissions across strains and populations.