Fig. 5

Hypothetical infection delay curve for region-at-risk A caused by a lockdown, following an outbreak beginning in region B. At time \(t=0\), location B would be the only infected region—as the outbreak location. At this time, a lockdown would allow region A to gain approximately 6.6 days (y-axis) until its first case of COVID-19. If the disease were to spread unmitigated until time \(t=30\) days, a lockdown would provide a gain of only 2 days before region A’s first case. At the 40-day mark following an outbreak in region B, without any intervention, region A would already be infected. Thus, a lockdown intervention at this point would have no ability to delay the onset of infection, with a y-axis value of 0