As COVID-19 is rapidly spreading across the globe, I have been trying for some time to come up with an interesting COVID-19 problem to address with statistics, in particular with Bayesian models. After examining some data, it was clear that at certain date, the growth of new cases stopped being exponential, which implies the distribution of new cases changes. Also, that date varies among different countries. The aim of the study is to identify the date when the distribution of new COVID-19 cases in a particular country changes. This can help policy maker evaluate the effectiveness of interventions, such as social distance measure. For detailed report and implementation, you can find them at my GitHub repo.