Dynamic Analysis of Social Distancing Ratio, Isolation Rate and Transmission Coefficient in COVID-19 Epidemic for Many Countries by SIQR Model

Recently SIQR model was proposed by Odagaki as the modification of conventional SIR model by adding the term for isolation of infected persons, Q(Quarantined). The exponent λ of the exponential function expressing the number of newly tested positive persons was defined as an linear equation explicitly with three important parameters, transmission coefficient, social distancing ratio x and isolation rate q. In this study, applying this model to the number of positive persons in publicly available database, daily λ values are regression analyzed, and social distancing ratio and isolation rate are derived. Analyses for 7 countries including Japan, Taiwan, South Korea, and western countries are performed and determine the dynamic locus of q-x relation on the q-x plane during epidemic propagation. Finally, the remaining parameter, the transmission coefficient is shown to closely relate to the maximum λ, λ _max , and λ _max (transmission coefficient) is characterized as a specific value for each country. Then, the magnitude of λ _max is combined with the value of λ _min to influence the total number of new cases until the convergence stage.