Two questions concerning the Covid-19 disease spread are addressed: can we identify and quantify the relative importance of the different dominant transmission routes of the SARS-CoV-2 virus using mathematical models?; can we construct a disease spread model from the mechanics of the dominant routes, thus identified? To these ends, the probability of infection caused by inhaling virus-laden droplets and their desiccated nuclei (aerosols) from a typical human cough, are individually calculated. Combined with molecular collision theory adapted to calculate the frequency of contact between the susceptible population and the aerosol cloud, infection rate constants are derived ab initio, leading to a Susceptible-Exposed-Infectious-Recovered (SEIRD) model applicable for any respiratory event - vector combination. Viral load, infectious dose, and dilution of the respiratory jet/puff by the entrained air are shown to mechanistically determine specific physical modes of transmission and variation in the corresponding basic reproduction number, from first-principle calculations.

Swetaprovo Chaudhuri is an Associate Professor at the Institute for Aerospace Studies, University of Toronto. He works in turbulent reacting and multiphase flows and is known for his contributions on turbulent flame stabilization, propagation, and structure using experiments, theory, and computations. He earned his Ph.D. from the University of Connecticut. Subsequently, he worked at Princeton University as research staff and then as a faculty member at the Indian Institute of Science. Prof. Chaudhuri has authored/co-authored over hundred articles in journals, conferences, and books and has been honored by several organizations. He is an elected Associate Fellow of the American Institute of Aeronautics and Astronautics and is a member of its Propellants and Combustion technical committee.

Related publications:

S. Chaudhuri, S. Basu, A. Saha, Analyzing the dominant SARS-CoV-2 transmission routes toward an ab initio disease spread model, Physics of Fluids 32, 123306 (2020); https://doi.org/10.1063/5.0034032

S. Chaudhuri, S. Basu, P. Kabi, V. Unni, A. Saha, Modeling the role of respiratory droplets in Covid-19 type pandemics, Physics of Fluids 32, 063309 (2020); https://doi.org/10.1063/5.0015984

S. Basu, P. Kabi, S. Chaudhuri, A. Saha, Insights on drying and precipitation dynamics of respiratory droplets from the perspective of COVID-19, Physics of Fluids, Physics of Fluids 32, 123317 (2020); https://doi.org/10.1063/5.0037360

S. Sharma, R. Pinto, A. Saha, S. Chaudhuri, S. Basu, On Secondary Atomization and blockage of surrogate cough droplets in single and multi-layer face masks, (2020) https://arxiv.org/abs/2010.00591. In press Science Advances