Lifting Lockdown Control Measure Assessment: From Finite to Infinite-dimensional Epidemic Models for COVID-19

The main focus of this chapter is on public health control strategies which are currently the main way to mitigate COVID-19 pandemic. We introduce and compare compartmental models of increasing complexity for COVID-19 transmission to describe dynamics of the disease spread. We begin by considering an SEAIR model including basic characteristics related to COVID-19. Next, we shall pay attention to age-structure modeling to emphasis the role of age-group individuals on the disease spread. A Model with constant delay is also formulated to show the impact of the latency period on the severity of COVID-19. Since there is evidence that for COVID-19 disease, important relationships exist between what is happening in the host and what is occurring at the population level, we shall link the basic model to in-host dynamics through the so-called threshold-type delay models. Finally, we will include demographic effects to the most complex models and we will conduct rigorous bifurcation analysis to quantify possible factors responsible for disease progression.