Eighty untreated low-risk Thai adults with acute influenza provided duplicate daily oropharyngeal swabs for 14 days with qPCR viral density. Growth-and-decay fit best, while exponential decay was most parsimonious. Median half-life was 10.3 hours: 9.6 for influenza A and 14.0 for B. Simulations suggested 148 per arm gives over 90% power to detect 40% faster clearance; more variability raises sample needs, while four swabs per day could reduce them to 81 per arm at over 80% power.
Key findings
- Median half-life 10.3 h; A 9.6 and B 14.0; 148/arm gives >90% power for 40% acceleration; doubled variability may require 232/arm despite 60% effect; four swabs/day may reduce to 81/arm at >80% power.
Why this matters globally
The framework can make phase II antiviral trials more sensitive and efficient and supports rapid drug comparison during pandemic preparedness.
Thai researcher contribution
Phrutsamon Wongnak, Tim Seers, Podjanee Jittamala, Mallika Imwong, William Schilling and Nicholas J. White conducted the study with Thai participants through Mahidol's tropical-medicine network.
Limitations to consider
Eighty low-risk adults do not represent children, older, pregnant, comorbid or severe cases. qPCR measures RNA, not viable virus, infectiousness or recovery. Oropharyngeal kinetics may differ from other sites, and simulation validity depends on model assumptions.