Hospital Admission and Social Distancing : An SEIR Model with Constrained Medical Resources

COVID-19 is a highly contagious disease and has been spread to most countries of the world with unprecedented transmission speed. Medical resources and treatments provided by the healthcare system are most critical to reduce the mortality rate of COVID-19 and to contain the spread of COVID-19 by isolating infectious individuals. We introduce a modified SEIR model with consideration of individuals’ access to limited medical resources to characterize the vital role of critical medical resources during the pandemic. We discuss how the three different hospital admission policies (hierarchy, mixed, and Fangcang sheltered healthcare system) affect the spread of the disease and the number of deaths and infections. We find that Fangcang shelter system results in the least number of infections, deaths as well as occupied beds among all three systems. In addition, when the hospital capacity is relatively high or transmission rate of the mildly infected patient is not ignorable, a mixed system can result in a lower number of infections and deaths but higher occupied beds than a hierarchy system because it prevents the disease transmission to a great extent. Public policies of social distancing play an important role in moderating the spreads overtime. We investigate the performance of the three healthcare systems under a static social distancing policy. We find that, under a static social distancing policy, a Fangcang shelter system results in the largest reduction in infections and deaths. Moreover, we conduct simulations on two types of dynamic lockdown policies and find that an effective dynamic lockdown policy should smooth the burden of a healthcare system and keeping minimum disruption of economic activities. That is, a lockdown that occurs either too early or two late could result in more deaths and infections