Background: The global spread of the COVID-19 pandemic has become the most fundamental threat to human lives. In the absence of vaccines and effective therapeutical solutions, non-pharmaceutic interventions have been a major way to control the epidemics. Relaxed mitigation interventions can slow down the epidemics but cannot control it well, while strict suppression interventions can efficiently halt the spread of epidemics, bringing negative effects on economics and people’s daily lives. Hence, suppression strategy and mitigation strategy play different roles in manupulating the epidemic curves.
Methods: Here, we propose a mathematical model to understand the rols of suppression and mitigation in changing the epidemic dynamics. By connecting the infection level with the consideration of the medical resources and a tolerence parameter, a combined intervention strategy of suppression and mitigation is proposed. Results: The combined intervention strategy is able to adaptively change with the infection level, resulting in a periodic wave of controlled infections. Depending on the tolerance level, the mitigation strategy can be adaptively switched on or off. The combined intervention can efficiently reduce the numbers of deaths and confirmed cases, and keep the infection within a low level, while such a wave of infection may exist for a long time before the availability of vaccines.
Conclusion: In order to control the epidemics, policy-makers have to consider the issues of human lives and economics. To solve such a dilemma, we propose a combined intervention stategy of suppression and mitigation, which can adaptively alternate with the epidemic dynamics. The combined strategy of suppression and mitigation is able to effectively control the epidemics within a low level, it can also reduce the negative effect on economics and human’s normal lives.