Coronavirus Disease 2019 Epidemic Doubling Time in the United States Before and During Stay-at-Home Restrictions

J Infect Dis. 2020 Oct 13;222(10):1601-1606. doi: 10.1093/infdis/jiaa491.

Abstract

Background: Coronavirus disease 2019 (COVID-19) has spread rapidly in the United States since January 2020.

Methods: We estimated mean epidemic doubling time, an important measure of epidemic growth, nationally, by state, and in association with stay-at-home orders.

Results: The epidemic doubling time in the United States was 2.68 days (95% confidence interval [CI], 2.30-3.24 days) before widespread mitigation efforts, increasing by 460% to 15 days (12.89-17.94 days) during the mitigation phase. Among states without stay-at-home orders, the median increase in doubling time was 60% (95% CI, 9.2-223.3), compared with 269% (95% CI, 277.0-394.0) for states with stay-at-home orders.

Conclusions: Statewide mitigation strategies were strongly associated with increased epidemic doubling time.

Keywords: COVID-19; SARS-CoV-2; coronavirus; epidemic doubling time.

MeSH terms

  • Betacoronavirus*
  • COVID-19
  • Coronavirus Infections / epidemiology*
  • Coronavirus Infections / prevention & control*
  • Coronavirus Infections / transmission
  • Coronavirus Infections / virology
  • Epidemiological Monitoring*
  • Humans
  • Pandemics / prevention & control*
  • Pneumonia, Viral / epidemiology*
  • Pneumonia, Viral / prevention & control*
  • Pneumonia, Viral / transmission
  • Pneumonia, Viral / virology
  • Quarantine / methods*
  • SARS-CoV-2
  • Time Factors
  • United States / epidemiology