Understanding the present status and forecasting of COVID?19 in Wuhan

Toshihisa Tomie

In order to understand the behavior of the general epidemic, the influenza epidemic in Japan over the past decade is shown in Fig. 1 (ref. 1) . The duration of influenza epidemics was four to six weeks. To avoid complexity, epidemics of three years are shown in Fig. 2 . An epidemic can be described by a Gaussian around the peak of the epidemic. The 2019 epidemic, which is referred as JpnInf2019 in the following, has the smallest deviation from a Gaussian and has a shorter epidemic period. As shown by a solid line in Fig. 2 , the epidemic of JpnInf2019 can be described by a Gaussian with a peak at 3.65 week and the number of new patients of 56 people at fixed observatories of diseases, and the "decay constant" which is the time duration between the peak and the time when the number of new infections decreases to 1/e of the peak value is 2.6 weeks. Although the full width at half maximum (FWHM) is common as a descriptive term for a Gaussian, the term "decay constant" is used to simplify the formula. FWHM equals to 1.67 "decay constant".