Fig 4. Effect of step-wise hard lock-down.

(a) Flattening the infectious curve by hard lockdown. Rapidly isolating a large population fraction is effective in mitigating the epidemic spreading. (b) Modeling hard lockdown: high μ_ld (orange) is active for four days to isolate and protect a large population fraction rapidly (blue). As an example, we show μ_ld = 0.28d⁻¹ if t ∈ [10, 14]. It results in protecting about 68% of the population in two days. Higher values, e.g. μ_ld = 0.65d⁻¹ would protect 93% of the population at once. (c) Google Mobility Report visualization [30] for analysed countries, around the date of measures setting. Each line reports the mean in mobility change across Retail & Recreation, Grocery & Pharmacy, Transit stations, and Workplaces, around the date of implementation of the measures. A minimum of four days (from top to bottom of steep decrease) is required for measures to be fully effective. Abbreviations explanation: AT = Austria, CH = Switzerland, DK = Denmark, IL = Israel, IR = Ireland, LO = Lombardy.