[Comparative Analysis of International Coronavirus Disease 2019 Contact-Tracing, Isolation, and Quarantine (TIQ) Policies and Simulation of Policy Effects].

Contact-tracing and isolation policies implemented by many countries during the novel coronavirus disease 2019 (COVID-19) pandemic have demonstrated significant effectiveness in disease containment. However, there are no standardized guidelines or indicators for contact-tracing policies in the face of new infectious diseases or variants of concern. The present study reviewed contact-tracing and isolation processes, economic incentives, and policy evaluation models for COVID-19 in major countries. In addition, a policy-effect simulation was conducted using a COVID-19 Agent-based Simulator (Covasim) model applied to domestic data. The present study introduces cases from 13 countries including Japan, Singapore, and Australia. The Covasim model analysis suggests that maintaining a certain level of contact-tracing is crucial, because the savings in COVID-19 tests when increasing the contact-tracing rate to >60% are not substantial. When supplemented by the issues raised in this study, contact-tracing, isolation, and quarantine (TIQ) policy can be an effective strategy for infectious disease prevention. Moreover, standardized evaluation metrics for TIQ policies should be developed to prepare for emerging infectious diseases. During the COVID-19 pandemic, many countries have implemented TIQ policies to control spread of the disease. Based on a review of the countries' policies and their respective evaluations, we determined the elements to be considered when implementing such policies. The Covasim model adopted from domestic data can be used to evaluate policy effectiveness. TIQ policy that increases participation and acceptance could be an effective strategy for controlling infectious diseases. Standardized TIQ policy evaluation indicators must be developed for efficient policy simulations of future novel infectious disease outbreaks.