Abstract for: Modeling the Transmission Dynamics of SARS-CoV-2 and the Effects of Intervention Timing on COVID-19 Incidence
Here I describe studies of the novel coronavirus SARS-CoV-2 using systems that combine mathematical models of infectious disease transmission and Bayesian inference approaches. In the first study mobility and human case data are used in conjunction with a model-inference system to infer critical epidemiological characteristics associated with SARS-CoV-2 in China during the mid-January 2020 initial growth and spread of the virus. We find that the vast majority of COVID-19 infections were undocumented and that these silent infections supported the bulk of transmission both within and between communities. We next applied a similar model-inference system in conjunction with county-level observations of reported infections and deaths in the US and human mobility data, to quantify changes of disease transmission rates in US counties from March 15, 2020 to May 3, 2020. We find significant reductions of the effective reproductive number in major metropolitan areas in association with social distancing and other control measures. Counterfactual simulations indicate that, had these same control measures been implemented just 1-2 weeks earlier, a substantial number of cases and deaths could have been averted. We also examine the effects of delays in re-implementing social distancing following a relaxation of control measures. A longer response time results in a stronger rebound of infections and death. Our findings underscore the importance of early intervention and aggressive response in controlling the COVID-19 pandemic. <> Jeffrey Shaman is a Professor in the Department of Environmental Health Sciences and Director of the Climate and Health Program at the Columbia University Mailman School of Public Health. He uses mathematical and statistical models to describe, understand, and forecast the transmission dynamics of infectious disease systems, and to investigate the broader effects of climate and weather on human health.