Global convergence of COVID-19 basic reproduction number and estimation from early-time SIR dynamics

Gabriel G. Katul; Assaad Mrad; Sara Bonetti; Gabriele Manoli; Anthony J. Parolari

The parameters γ and β encode the main properties of the epidemics and the 81 population response to it. The γ = 1/D is generally interpreted as the inverse of the 82 mean recovery time D. The D varies with the nature of the disease and the recovery 83 from it which depends on the medical facilities and resources available. For COVID-19, 84 the best information on the speed of recovery comes from a World Health Organization 85 study examining more than 55000 cases in China [19] . They found that for mild illness, 86 the time from the onset of symptoms to natural recovery is, on average, 14 days. This 87 estimate was also supported in other published studies (e.g., [20] ), though as much as Hence, β = k T r . Factors such as hand-washing and sanitizing reduce T r whereas social 96 distancing, self-isolation, and closure of public spaces reduce k. It is evident that dI/dt 97 will be positive (outbreak) or negative (epidemic contained) depending on the sign of . CC-BY-NC 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.