Fig. 6.

Schematic illustration of the factor $c(t)$, representing the effect of NPIs and adaptive behavioural changes on transmission. $L_1$ represents the known duration (and timing) of the first lockdown as imposed by governments. $T_0$ is the number of days in the series prior to the gradual contact reductions early in the pandemic (estimated). $T_1$ ($>T_0$) is the day the first lockdown begins (informed by data). $T_2$ is the number of days for the ramp of increasing transmission after first lockdown to return to baseline $c(t)=1$ and determines the slope that distinguishes the two panels: (a) $T_2\to \infty$; (b) $T_2=120$ days.