Before revision:  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 .
After revision:  COVID-19 grew into a world-wide pandemic. Transmission by pre-symptomatic and asymptomatic viral carriers rendered intervention and containment of the disease extremely challenging. Based on reported infection case studies, we construct an epidemiological model that focuses on transmission around the symptom onset time distribution, which we calibrated , into the percentage of the latent, pre-symptomatic and symptomatic groups through a novel mathematical procedure .