The impact of surgical mask-wearing, contact tracing program, and vaccination on COVID-19 transmission in Taiwan 2020-2022: a modelling study

The effectiveness of interventions such as public mask-wearing, contact tracing, and vaccination presents an important lesson for control of the further COVID-19 outbreaks without of whole country lockdowns and the restriction of individual movement. We simulated different scenarios of COVID-19 waves in Taiwan from 2020 to the beginning of March 2022 and considered the following interventions: travel restrictions, quarantine of infected individuals, contact tracing, mask-wearing, vaccination, and mass gathering restrictions. We propose an epidemiological compartmental model modified from the susceptible-exposed-infectious-removed (SEIR) model and derive a formula for the basic reproduction number (R0) describing its dependence on all investigated parameters. The simulation results are fitted with the official Taiwanese COVID-19 data. Thus, the results demonstrate that the fast introduction of the interventions and maintaining them at a high level are able the outbreak control without strict lockdowns. By estimation of the R0, it was shown that it is necessary to maintain on high implementation level of both non- and pharmaceutical intervention types to control the COVID-19 transmission. Our results can be useful as advice or recommendation for public health policies, and our model can be applied for other epidemiological simulation studies.