Estimating the size of COVID-19 epidemic outbreak

Chakrit Pongkitivanichkul; Daris Samart; Takol Tangphati; Phanit Koomhin; Pimchanok Pimton; Punsiri Dam-O; Apirak Payaka; Phongpichit Channuie

One of the countries which has not reached the expected inflection point yet is Italy. The results of fitting with data for various values of n is shown in Fig.5 . Our results suggest that the early stage of epidemic in Italy is not in a controlled stage since the data in early days fit better with a higher value of n. However, we do not pursue the exact value of n of the country before the expected inflection point because of the large uncertainty coming with other parameters especially the size of the epidemic, a which we will discuss later. Instead, we first focus on using n = 1 for countries in this phase. Some of them are in an early stage of epidemic with insufficient amount of data leading to a large uncertainty on parameter fits. Many of them have an official number of infected cases that might be under investigated due to limited resources in testing kits. We will focus on 5 European countries (Italy, Spain, France, Germany, and Switzerland) since their outbreaks have been happening for a while and their health system are somehow capable of reporting data. Examples of the results from parameter fit with n = 1 are given in Fig.6 where the error of parameter fits are displayed in TA-BLE II.