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Quantitative Aerobiologic Analysis of an Influenza Human Challenge-Transmission Trial
P. JACOB BUENO DE MESQUITA, Noakes Catherine, Donald Milton, University of Maryland School of Public Health
Abstract Number: 499
Working Group: The Role of Aerosol Science in the Understanding of the Spread and Control of COVID-19 and Other Infectious Diseases
Abstract
Despite evidence that airborne transmission contributes to influenza and other respiratory infection epidemics or pandemics, limited knowledge of the infectiousness of human cases hinders pandemic preparedness. We used airborne viral source strength and indoor CO2 monitoring from the largest human influenza challenge-transmission trial (EMIT: Evaluating Modes of Influenza Transmission, ClinicalTrials.gov number NCT01710111) to compute an airborne infectious dose generation rate q=0.11 (95% CI 0.088, 0.12)/h and calculate the quantity of airborne virus per infectious dose =1.4E+5 RNA copies/quantum (95% CI 9.9E+4, 1.8E+5). We then compared these calculated values to available data on influenza airborne infectious dose from several previous studies, and applied the values to dormitory room environments to predict probability of transmission between roommates. Transmission risk from typical, moderately to severely symptomatic influenza cases is dramatically decreased by exposure reduction via increasing indoor air ventilation. The minority of cases who shed the most virus (i.e., supershedders) may pose great risk even in well-ventilated spaces. Our modelling method and estimated infectiousness provide a groundwork for a) epidemiologic studies of respiratory infection (including SARS-CoV-2) transmission in non-experimental settings and b) evaluation of the extent to which airborne exposure control strategies could limit transmission risk.