The COVID-19 has infected more than 462 ,000 people globally and resulted in over 20 ,000 deaths as of March 26 , 2020. Swift government response to contain the outbreak requires accurate and continuous census of the infected population, particularly with regard to viral carriers without severe symptoms. We take on this task by converting the symptom onset time distribution, which we calibrated, into the percentage of the latent, pre-symptomatic and symptomatic groups through a novel mathematical procedure. 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  .
 COVID-19 has infected more than 823 ,000 people globally and resulted in over 40 ,000 deaths as of April 1 , 2020. Swift government response to contain the outbreak requires accurate and continuous census of the infected population, particularly with regards to viral carriers without severe symptoms. We take on this task by converting the symptom onset time distribution, which we calibrated, into the percentage of the latent, pre-symptomatic and symptomatic groups through a novel mathematical procedure. 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 point out the significance of a universal decay rate of -0.32/day in the final eradication of the disease .
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