In the beginning of December, 2019, Covid-19 virus that slipped from animals to humans in Wuhan city, China caused an outbreak of respiratory illness. A number of the statistical, dynamic and mathematical models of the Covid-19 outbreak including the SEIR model have been developed to analyze its transmission dynamics 1, 2, 3, 4, 5 . Although these epidemiological models are useful for estimating the dynamics of transmission, targeting resources and evaluating the impact of intervention strategies, the models require parameters and depend on many assumptions. Unlike system identification in engineering where the parameters in the models are estimated using real data, at the outbreak, estimated parameters using real time data are not readily available 6, 7 Most analyses used hypothesized parameters and hence do not fit the data very well. The accuracy of forecasting the future cases of Covid-19 using these models may not be very high. Timely interventions are needed to control the serious impacts of Covid-19 on health.
To overcome limitations of the epidemiological model approach, and assist public health planning and policy making, we develop an AI based method for real time forecasting of the new and cumulative confirmed cases of Covid-19 in total and provinces/ cities across China. We also forecast the possible trend and plateau of Covid-19 transmission in China and group the provinces/cities into clusters according to the dynamic patterns of Covid-19 transmission. The analysis is based on the surveillance data of the confirmed Covid-19 cases in China up to February 18, 2020.
Data on the confirmed cases of Covid-19 from January 11, 2020 to January 20, 2020, and from January 21, 2020 to February 27, 2020, were from Surging News Network (https://www.thepaper.cn/) and WHO (https://www.who.int/emergencies/diseases/novelcoronavirus-2019/situation-reports), respectively. WHO took the lab confirmed case as the confirmed cases from January 21, 2020 to February 13, 2020 and took the sum of the number of the clinical confirmed and lab conformed cases as the number of the confirmed cases after Modified auto-encoders (MAE) 8, 9 were used to forecast the number of the accumulative and new confirmed cases of Covid-19. Unlike the classical auto-encoder where the number of nodes in the layers usually decreases from the input layer to the latent layers, the numbers of the nodes in the input, the first latent layer, the second latent layer and output layers in the MAE were 8, 32, 4 and 1, respectively ( Figure 1 ). We view a segment of time series with 8 days as a sample of data and take 128 segments of time series as the training samples. One element from the dada matrix is randomly selected as a start day of the segment and select its 7 successive days as the other days to form a segment of time series. Let be the index of the segment and , be the column index of the matrix that was selected as the starting day. The ./ segment time series The potential cumulative confirmed cases of Covid-19 in China was observed to reach the plateau (83,401) on April 20, 2020. Figure S1 plotted the national reported and fitted curves of the cumulative confirmed cases in China from January 20, 2020 to February 27, 2020. To further examine the accuracy of forecasting, Table 1 where the data from January 20, 2020 to February 27, 2020 were used to fit the MAE model. In the table, we listed 1 day-step to 10 daystep forecasting errors, respectively, i.e., the errors of using the current reported cases to forecast future s day cases. Table 1 showed that the average errors of the forecasting did not strictly increase as the number-steps for forecasting increased due to fluctuations of the data. Forecasting accuracy was very high.
9 Figure 3 presented the forecasted curves of cumulative confirmed cases of Covid-19 across 31
China as a function of days from January 11, 2020 to April 20, 2020. We observed from Figure 3 that the times of different provinces/cities entering the plateau will be different, ranging from Jan 21, 2020 to April 20, 2020. Xizang first entered the plateau at Jan 21 followed by Macao on Jan 26 and Qinghai on Jan 28. Hubei province will be one of the last to enter the plateau (70,019)
around April 20, 2020, most provinces/cities will enter the plateau around middle of March. We In addition to the geographic locations that affected the transmission of Covid-19, the healthcare resources and economic and social activities may also affect the transmission dynamics of Covid-19 as the cluster of Shanghai, Hongkong, Beijing, Shandong and Sichuan. And Fujian Guangxi, Hebei, Jilin and Tianjin formed a cluster, but these five provinces/cities are not located in the same geographic area. They may have similar economic relationships with Wuhan, healthcare resources and take similar interventions to control of the spread of Covid-19.
As an alternative to epidemiologic transmission model, we used MAE to forecast the real-time Figure S1 . The national reported and fitted curves of the cumulative confirmed cases of Covid-19 in China from January 11, 2020 to February 27, 2020, where the red curve was the reported and green curve was the fitted.