Fig. 3: The impact of PI parameters and contagiousness on infectious disease controllability.
Contagiousness and the capacity to reach the target number of ICU cases. Panels a and b show how the time required to reach the ICU target (represented by colors as in previous figures) depends on variant type and PI values. For combinations of P- and I-parameters outside the colored region, the system is unstable (compare insets in Panels a and b). Panel c shows the time required to reach the target for low and high contagiousness and for different values of γP and γI. A steep increase in time to reach the target indicates when controllability is lost. In Panel (d), the red volume contains the set of all parameters for which the target can be reached. The points A–E are on the boundary of this parameter set and correspond to those in (c) illustrating loss of controllability. Panel e shows the number of patients in intensive care units over time (data extracted from data.gouv.fr) in blue overlain with the national lockdown policies with the red vertical lines (note that a combination of more or less restrictive measures were carried out throughout the pandemic which are not reported in this Figure).
