Evaluating the effectiveness of social distancing interventions against COVID-19

Laura Matrajt; Tiffany Leung

The strategy that targets adults over 60 and children results in 16,500 fewer cases (57% less than baseline) at epidemic peak ( Figure 3 , panels D-F) compared to baseline. In comparison, the adults-only strategy yields 12,000 fewer ascertained cases (41% less than baseline) at the epidemic peak for 25% compliance in younger adults (adults under 60 yo, Figure 3 , panel D). At a higher compliance of 75% and 95% in adults, the epidemic peak is reduced even more, with 21,000 and 24,000 fewer cases ascertained at the peak (72 and 82% less) respectively ( Figure 3 , panel E, F), and the epidemic curve grows at a slower rate. Of the four different interventions, the all-groups strategy, which reduces the contacts in all age groups, decreases the epidemic peak the most and results in the slowest growth rate, as expected. Even with low compliance (25%) in the younger-adult groups, the all-groups strategy yields 20,000 fewer cases ascertained (68% less) at the epidemic peak ( Figure 3 , panel D). With higher compliance (95%) in adults, the all-groups strategy results in even fewer cases ascertained at the peak (27,000 fewer cases or 92% less; Figure 3 , panel F). However, our results suggest that all these interventions can result in new epidemic curves once the interventions are lifted.