COVID-19: large-scale containment averted an estimated 62 million-plus cases

  • Hsiang S & al.
  • Nature
  • 8 Jun 2020

  • curated by Liz Scherer
  • Clinical Essentials
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Takeaway

  • 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.

Key results

  • 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>

Study design

  • 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.

Limitations

  • Bias for case detection trends.
  • No focus on other confounders.