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Volume 27, Number 9—September 2021
Research

Estimating the Impact of Statewide Policies to Reduce Spread of Severe Acute Respiratory Syndrome Coronavirus 2 in Real Time, Colorado, USA

Andrea G. Buchwald1, Jude Bayham, Jimi Adams, David Bortz, Kathryn Colborn, Olivia Zarella, Meghan Buran, Jonathan Samet, Debashis Ghosh, Rachel Herlihy, and Elizabeth J. CarltonComments to Author 
Author affiliations: Colorado School of Public Health, Aurora, Colorado, USA (A.G. Buchwald, O. Zarella, M. Buran, J. Samet, D. Ghosh, E.J. Carlton); Colorado State University, Fort Collins, Colorado, USA (J. Bayham); University of Colorado, Denver, Colorado, USA (J. Adams); University of Colorado, Boulder, Colorado, USA (D. Bortz); University of Colorado School of Medicine, Aurora (K. Colborn); Colorado Department of Public Health and Environment, Denver (R. Herlihy)

Main Article

Figure 1

Emergence of COVID-19, Colorado, USA, 2020, showing policy-based responses (A) and definition of 4 distinct social distancing phases (B) corresponding with early closures (phase 1, March 17‒25); statewide stay-at-home (phase 2, March 26‒April 26), statewide partial transition to safer-at-home (phase 3, April 27–May 8); statewide safer-at-home (phase 4, May 5–June 3). Social distancing parameters were estimated at 4 points during March‒June by using model fitting procedures and reported case data (fits 1 and 2) and hospital census data (fits 3 and 4). In light of the 5.1 day mean incubation period, the ≈7-day lag between symptom onset and case report, and the ≈8-days between symptom onset and hospitalization based on state records, there are ≈12 and 13 day lags between infection and case report, and infection and hospitalization, respectively (gray boxes). Thus, at each model fit, we could estimate social distancing parameters reflecting transmission conditions up to 12 (fits 1 and 2) or 13 (fits 3 and 4) days before the fit date. Asterisks (*) indicate estimate generated for only part of the period. COVID-19, coronavirus disease; P, phase.

Figure 1. Emergence of COVID-19, Colorado, USA, 2020, showing policy-based responses (A) and definition of 4 distinct social distancing phases (B) corresponding with early closures (phase 1, March 17‒25); statewide stay-at-home (phase 2, March 26‒April 26), statewide partial transition to safer-at-home (phase 3, April 27–May 8); statewide safer-at-home (phase 4, May 5–June 3). Social distancing parameters were estimated at 4 points during March‒June by using model fitting procedures and reported case data (fits 1 and 2) and hospital census data (fits 3 and 4). In light of the 5.1 day mean incubation period, the ≈7-day lag between symptom onset and case report, and the ≈8-days between symptom onset and hospitalization based on state records, there are ≈12 and 13 day lags between infection and case report, and infection and hospitalization, respectively (gray boxes). Thus, at each model fit, we could estimate social distancing parameters reflecting transmission conditions up to 12 (fits 1 and 2) or 13 (fits 3 and 4) days before the fit date. Asterisks (*) indicate estimate generated for only part of the period. COVID-19, coronavirus disease; P, phase.

Main Article

1Current affiliation: University of Maryland School of Medicine, Baltimore, Maryland, USA.

Page created: June 02, 2021
Page updated: August 17, 2021
Page reviewed: August 17, 2021
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