Fig. 1
From: Modeling-based design of adaptive control strategy for the effective preparation of ‘Disease X’
Model framework schematic. a Changes in population immunity levels. The immunity level ranks from low to high as low-level immunity, basic immunity and boosted immunity. Immunity enhancement through vaccination is considered from low immunity level to high immunity level and immunity wanning is considered from high immunity level to low immunity level. Specifically, for individuals who have never been infected, immunity can only be obtained through vaccination and for individuals who have been infected, natural immunity are acquired at the boosted immunity level. b Flowchart describing COVID-19 transmission, immunity waning considering primary and reinfection