- Large-scale, nonpharmaceutical, anticontagion policies across 6 countries to mitigate SARS-CoV-2 spread appear to have prevented or delayed ~62 million cases (55-66 million) of COVID-19.
Why this matters
- Results suggest continuation of containment interventions (e.g., shelter at home, limited travel) to contain SARS-CoV-2 transmission and acquisition during sporadic outbreaks.
- Without mitigation, early COVID-19 infections grow by an average 43% per day (standard error [SE], 5%).
- Excluding Iran (where high rates are unexplained), the average daily growth rate is 38% (SE, 5%).
- Based on China, the pattern under 3 combined policies led to:
- Reduced infection growth by −0.026 (SE, 0.046) in week 1,
- Steeper reductions in week 2, by −0.20 (SE, 0.049), and
- Stabilizing in week 3 at −0.28 (SE, 0.047).
- Overall, all policies combined slowed daily average infection growth rates (SEs):
- China: −0.252 (0.045; P<.001>
- South Korea: −0.248 (0.089; P<.01>
- Italy: −0.24 (0.068; P<.001>
- Iran: −0.355 (0.063; P<.001>
- France: −0.123 (0.019; P<.001>
- United States: −0.084 (0.03; P<.01>
- Empirical evaluation of direct effects of anticontagion policies across China, France, Italy, Iran, South Korea, and the United States, from earliest available dates to 6 April 2020.
- Funding: None disclosed.
- Bias for case detection trends.
- No focus on other confounders.