Frontiers in Physics ( IF 1.9 ) Pub Date : 2020-07-06 , DOI: 10.3389/fphy.2020.00311 Seo Yoon Chae , KyoungEun Lee , Hyun Min Lee , Nam Jung , Quang Anh Le , Biseko Juma Mafwele , Tae Ho Lee , Doo Hwan Kim , Jae Woo Lee
We consider the pandemic spread of COVID-19 in selected countries after the outbreak of the SARS-CoV-2 coronavirus in Wuhan City, China. We estimated the infection rate and the initial individuals infected with COVID-19 by using officially reported data from the early stages of the epidemic for a model of susceptible (S), infectible (I), quarantined (Q), and officially confirmed recovered (Rk) populations (the so-called SIQRk model). In the officially reported data, we know the number of quarantined cases and the officially reported number of recovered cases. We cannot know about recovered cases from asymptomatic patients. In the SIQRk model, we can estimate the parameters and the initial infections (confirmed cases + asymptomatic cases) from fitted values. We obtained an infection rate in the range β = 0.233 ~ 0.462, a basic reproduction number of