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Volume 26, Number 8—August 2020

Evaluating the Effectiveness of Social Distancing Interventions to Delay or Flatten the Epidemic Curve of Coronavirus Disease

Laura MatrajtComments to Author  and Tiffany Leung
Author affiliations: Fred Hutchinson Cancer Research Center, Seattle, Washington, USA

Main Article


Description of parameters used in the susceptible-exposed-infectious-removed mathematical model for evaluating the effectiveness of social distancing interventions on coronavirus disease*

Parameter Meaning Value Range Reference
1/σ Mean latent period 5.16 days 4.5–5.8 days (14)
1/γ Mean infectious period 5.02 days 3–9 days
β Transmission coefficient Calculated NA NA
С Contact matrix NA NA (19)
Total population
3.5 million
*NA, not applicable.
†Q. Bi, unpub. data,

Main Article

  1. Li  Q, Guan  X, Wu  P, Wang  X, Zhou  L, Tong  Y, et al. Early transmission dynamics in Wuhan, China, of novel coronavirus-infected pneumonia. N Engl J Med. 2020;382:1199207. DOIPubMedGoogle Scholar
  2. World Health Organization. WHO Director-General’s opening remarks at the media briefing on COVID-19 11 March 2020 [cited 2020 Mar 15].
  3. Johns Hopkins University and Medicine. Coronavirus resource center. COVID-19 global cases [cited 2020 Apr 2].
  4. Holshue  ML, DeBolt  C, Lindquist  S, Lofy  KH, Wiesman  J, Bruce  H, et al.; Washington State 2019-nCoV Case Investigation Team. Washington State 2019-nCoV Case Investigation Team. First case of 2019 novel coronavirus in the United States. N Engl J Med. 2020;382:92936. DOIPubMedGoogle Scholar
  5. Snohomoish County Washington. Local declaration of emergency Snohomish County 2020 Mar 4 [cited 2020 Mar 15].
  6. Washington State Department of Health. 2019 novel coronavirus outbreak (COVID-19) [cited 2020 Mar 15].
  7. Proclamation by the governor: amending proclamations 20–05 and 20–06; 20–07. Washington, USA. 2020 Mar 11 [cited 2020 Mar 15].
  8. Office of the Governor. Washington State. Inslee announces school closures in King, Snohomish and Pierce counties. 2020 Mar 12 [cited 2020 Mar 15].
  9. Proclamation by the governor: amending proclamations 20–05; 20–25, stay home–stay healthy. Washington, USA. 2020 Mar 23 [cited 2020 Apr 2].
  10. CBS News. Coronavirus updates from March 20, 2020 2020 [cited 2020 Mar 20].
  11. Schnirring  L. France orders lockdown to slow COVID-19 spread. CIDRAP News 2020 Mar 16. Center for Infectious Disease Research and Policy [cited 2020 Mar 16].
  12. Minder  R, Peltier  E. Spain, on lockdown, weighs liberties against containing coronavirus. The New York Times. 2020 Mar 15 [cited 2020 Mar 16].
  13. United States Census Bureau. Seattle-Tacoma-Bellevue metro area, Washington [cited 2020 Mar 15].
  14. Lauer  SA, Grantz  KH, Bi  Q, Jones  FK, Zheng  Q, Meredith  HR, et al. The incubation period of coronavirus disease 2019 (COVID-19) from publicly reported confirmed cases: estimation and application. Ann Intern Med. 2020; Epub ahead of print. DOIPubMedGoogle Scholar
  15. Wu  Z, McGoogan  JM. Characteristics of and important lessons from the coronavirus disease (COVID-19) outbreak in China: summary of a report of 72,314 cases from the Chinese Center for Disease Control and Prevention. JAMA. 2020;323:123942. DOIPubMedGoogle Scholar
  16. Novel Coronavirus Pneumonia Emergency Response Epidemiology Team. Vital surveillances: the epidemiological characteristics of an outbreak of 2019 novel coronavirus diseases (COVID-19)–China, 2020. China CDC Wkly. 2020;2:113–22 [cited 2020 Mar 15].
  17. Li  R, Pei  S, Chen  B, Song  Y, Zhang  T, Yang  W, et al. Substantial undocumented infection facilitates the rapid dissemination of novel coronavirus (SARS-CoV2). Science. 2020;eabb3221; Epub ahead of print. DOIPubMedGoogle Scholar
  18. Ferguson  NM, Laydon  D, Nedjati-Gilani  G, Imai  N, Ainslie  K, Baguelin  M, et al. Impact of non-pharmaceutical interventions (NPIs) to reduce COVID-19 mortality and healthcare demand. Imperial College London. 2020 Mar 16 [cited 2020 Mar 17].
  19. Wallinga  J, Teunis  P, Kretzschmar  M. Using data on social contacts to estimate age-specific transmission parameters for respiratory-spread infectious agents. Am J Epidemiol. 2006;164:93644. DOIPubMedGoogle Scholar
  20. Bedford  T. Cryptic transmission of novel coronavirus revealed by genomic epidemiology. Bedford Lab. 2020 Mar 2 [cited 2020 Mar 15].
  21. Office of the Governor. Washington State. Inslee announces statewide shutdown of restaurants, bars and expanded social gathering limits. 2020 Mar 16 [cited 2020 Mar 18].
  22. Ellyat  H. No lockdown here: Sweden defends its more relaxed coronavirus strategy. CNBC. 2020 Mar 30 [cited 2020 Apr 2].
  23. Qiu  H, Wu  J, Hong  L, Luo  Y, Song  Q, Chen  D. Clinical and epidemiological features of 36 children with coronavirus disease 2019 (COVID-19) in Zhejiang, China: an observational cohort study. Lancet Infect Dis. 2020;S1473-3099(20)30198-5; Epub ahead of print. DOIPubMedGoogle Scholar
  24. Lempel  H, Hammond  RA, Epstein  JM. Costs of school closure. The Brookings Institution. 2009 Sep 30 [cited 2020 Apr 2].
  25. Zhou  F, Yu  T, Du  R, Fan  G, Liu  Y, Liu  Z, et al. Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study. Lancet. 2020;395:105462. DOIPubMedGoogle Scholar
  26. US Centers for Disease Control and Prevention. Interim pre-pandemic planning guidance: community strategy for pandemic influenza mitigation in the United States: early, targeted, layered use of nonpharmaceutical interventions. Atlanta: The Centers; 2007.
  27. Hasell  J, Ortiz-Ospina  E, Mathieu  E, Ritchie  H, Beltekian  D, Roser  M. To understand the global pandemic, we need global testing—the Our World in Data COVID-19 Testing dataset, How many tests for COVID-19 are being performed around the world? Our World In Data [cited 2020 Mar 16].
  28. Zhao  J, Yuan  Q, Wang  H, Liu  W, Liao  X, Su  Y, et al. Antibody responses to SARS-CoV-2 in patients of novel coronavirus disease 2019. Clin Infect Dis. 2020;ciaa344; Epub ahead of print. DOIPubMedGoogle Scholar
  29. Klein  D, Hagedorn  B, Kerr  C, Hu  H, Bedford  T, Famulare  M, et al. Working paper–model-based estimates of COVID-19 burden in King and Snohomish counties through April 7, 2020 [cited 2020 Mar 16].–%20model-based%20estimates%20of%20COVID-19%20burden%20in%20King%20and%20Snohomish%20counties%20through%20April%207.pdf
  30. Prem  K, Liu  Y, Russell  TW, Kucharski  AJ, Eggo  RM, Davies  N, et al.; Centre for the Mathematical Modelling of Infectious Diseases COVID-19 Working Group. The effect of control strategies to reduce social mixing on outcomes of the COVID-19 epidemic in Wuhan, China: a modelling study. Lancet Public Health. 2020;S2468-2667(20)30073-6; [Epub ahead of print].PubMedGoogle Scholar
  31. Ferretti  L, Wymant  C, Kendall  M, Zhao  L, Nurtay  A, Abeler-Dörner  L, et al. Quantifying SARS-CoV-2 transmission suggests epidemic control with digital contact tracing. Science. 2020;eabb6936; Epub ahead of print. DOIPubMedGoogle Scholar
  32. World Health Organization. WHO Director-General’s opening remarks at the media briefing on COVID-19–16 March 2020 [cited 2020 Mar 18].
  33. Weiss  P, Murdoch  DR. Clinical course and mortality risk of severe COVID-19. Lancet. 2020;395:10145. DOIPubMedGoogle Scholar
  34. Wölfel  R, Corman  VM, Guggemos  W, Seilmaier  M, Zange  S, Müller  MA, et al. Virological assessment of hospitalized patients with COVID-2019. Nature. 2020; Epub ahead of print. DOIPubMedGoogle Scholar
  35. Wu  JT, Leung  K, Leung  GM. Nowcasting and forecasting the potential domestic and international spread of the 2019-nCoV outbreak originating in Wuhan, China: a modelling study. Lancet. 2020;395:68997. DOIPubMedGoogle Scholar
  36. Kraemer  MUG, Yang  C-H, Gutierrez  B, Wu  C-H, Klein  B, Pigott  DM, et al.; Open COVID-19 Data Working Group. The effect of human mobility and control measures on the COVID-19 epidemic in China. Science. 2020;eabb4218; Epub ahead of print. DOIPubMedGoogle Scholar
  37. Flaxman  S, Mishra  S, Gandy  A, Unwin  HJT, Coupland  H, Mellan  TA, et al. Imperial College COVID-19 Response Team. Report 13: estimating the number of infections and the impact of non-pharmaceutical interventions on COVID-19 in 11 European countries. 2020 Mar 30. [cited 2020 Mar 20].
  38. Tuite  AR, Fisman  DN, Greer  AL. Mathematical modelling of COVID-19 transmission and mitigation strategies in the population of Ontario, Canada. CMAJ. 2020 Apr 8 [Epub ahead of print].

Main Article

Page created: June 05, 2020
Page updated: July 17, 2020
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