Before revision:  We then estimate the reduction of the basic reproduction number R_0 under specific disease control practices such as contact tracing, testing and social distancing. Finally, in light of our model findings, we analyze the bell-shaped curves of epidemic evolution from various affected regions , and recommend measures to steer the pandemic to its final descent at a universal decay rate of -0.32/day  .
After revision:  We then estimate the reduction of the basic reproduction number R_0 under specific disease control practices such as contact tracing, testing , social distancing, wearing masks and staying at home. When these measures are implemented in parallel, their effects on R_0 multiply. For example, if 70\% of the general public wear masks and contact tracing is conducted at 60\% efficiency within a 4-day time frame, epidemic growth will be flattened in the hardest hit countries. Finally, we analyze the bell-shaped curves of epidemic evolution from various affected regions , and recommend measures to steer the pandemic to its final descent at a universal decay rate of -0.32/day .