The impact of surgical mask-wearing, contact tracing program, and vaccination on COVID-19 transmission in Taiwan from January 2020 to March 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 (R 0 ) 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 R 0 , 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.