Government Responses Matter: Predicting Covid-19 cases in US under an empirical Bayesian time series framework

Ziyue Liu; Wensheng Guo

Results based on US data up to March 26 th , 2020 are shown in Figure 2~4 . Two important observations can be made from these figures. There is no apparent slowing down yet for US trajectory based on either the observed trend or predicted trend. This indicates that US is still in its exponentially increasing phase in the near future. Figure 2 displays the results using Italy as prior. It shows that US and Italy have similar patterns and majority of the observed US data are in the 95% prediction intervals. This suggests that the trajectory in Italy serves as a good prior for the US prediction. Based on this prediction, on the next day as March 27 th , 2020, US may have as many as 108,595 cases. In about 10 days, the US case number will exceed 300,000 around April 4 th , 2020 shall the US policy responses have similarly effects as Italy.