Fig. 1

COVID-19 spread models on the network. a Compartmental structures. Susceptible individuals (\({{S}}\)) enter the latent period after being infected. After the latent period, they enter the pre-symptomatic stage, in which individuals are infectious but asymptomatic. Afterwards, some individuals develop symptoms, others remain asymptomatic, and individuals in \({{I}}_{\text{pre}}\), \({{I}}_{\text{sym}}\), and \({{I}}_{\text{asym}}\) are infectious. Some symptomatic individuals develop severe disease and are admitted to the hospital (\(H\)) for treatment, some of them die due to ineffective treatment (\(F\)), and the remaining infected individuals enter the compartment \({{R}}\) after recovery. Infected individuals who tested positive and their close contacts (which were successfully traced) enter the corresponding isolation compartment and follow the same disease course; if they do not enter other disease states after the isolation period (14 days) expires, they return to the corresponding non-isolation compartment. b The network structure before implementation of non-pharmacological interventions (NPIs). Individuals were represented as nodes in the network, and people of different age groups were distinguished by node color. The edges indicated the close contact between individuals, and the contact rates between individuals varied by age, individuals in the same age group were more closely connected. c The network structure after implementing NPIs. After the implementation of the NPIs, the individual will be isolated at home. The household members will still completely connect, but the connection with the outside of the family will be cut off