The trade-off between deaths by infection and socio-economic costs in the emerging infectious disease

COVID-19, caused by the novel coronavirus (SARS-CoV-2), is an emerging infectious disease (EID) with a relatively high infectivity and mortality rate. During the state of emergency announced by the Japanese government in the spring of 2020, citizens were requested to stay home, the number of infected people was drastically reduced without a legally-binding lockdown. It is well-acknowledged that there is a trade-off between maintaining economic activity and preventing the spread of infectious diseases. We aimed to reduce the total loss caused by the epidemic of an EID like COVID-19 in the present study. We focused on early and late stages of the epidemic and proposed a framework to reduce the total loss resulted from the damage by infection and the cost for the countermeasure. Mathematical epidemic models were used to estimate the effect of interventions on the number of deaths by infection. The total loss was converted into the monetary base and different policies were compared. In the early stage, we calculated the damage by infection when behavioral restrictions were implemented. The favorable intensity of the intervention depended on the basic reproduction number, infection fatality rate, and the economic impact. In the late stage, we calculated indicators and showed it depended on the ratio of the cost to maintain the hospitalization system to the monetary loss per deaths by infection which strategies should be adopted.