Effectiveness of Non-Pharmaceutical Intervention Against Local Transmission of COVID-19: An Individual-Based Modelling Study

Background: The outbreak of the novel coronavirus disease 2019 (COVID-19) has caused global transmission, and been spread all over the world. For those regions that are currently free of infected cases, it is an urgent issue to prevent and control the local outbreak of COVID-19 when there are sporadic cases. We aimed to evaluate the effects of non-pharmaceutical interventions, such as isolation, contact tracing, and physical distancing, against local transmission of COVID-19, and to forecast the epidemic dynamics after local outbreak of diseases under different control measures. Methods: For this computational modelling study, we developed an individual-based model (IBM) to simulate the transmission dynamics of COVID-19 from a microscopic perspective of individual-to-individual contacts and heterogenous among individuals. We simulated the effects of different levels of non-pharmaceutical interventions in controlling disease transmission after the appearance of sporadic cases. Through model simulations, we discussed the epidemic dynamics and evaluated the conditions of initiating different level responses in order to achieve better controls of the local transmission. Findings: Model simulations shown that isolation of infected cases and quarantine of close contacts alone would not eliminate the local transmission of COVID-19, and there is a risk of a second wave epidemics. Quarantine the second-layer close contacts can obviously reduce the size of outbreak. Moreover, to effectively eliminate the daily new infections in a short time, it is necessary to reduce the individual-to-individual contacts. Interpretation: IBM provides a numerical representation for the local transmission of infectious diseases, the model extends the compartmental models to include individual heterogeneity and the close contacts network. Through model simulation, we quantitatively analysis the transmission patterns of COVID-19 under different control measures. Combinations of self-isolation, quarantine of close contacts, and social distancing would be necessary to block the local transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Funding Statement: This work was supported by the National Natural Science Foundation of China under grant No.11971023 and No.11871371. Declaration of Interests: The authors declare that they do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted.