Spatially refined time-varying reproduction numbers of SARS-CoV-2 in Arkansas and Kentucky and their relationship to population size and public health policy, March – November 2020

• Type of Material: Article
• Authors: Maria D Politis, Icahn School of Medicine at Mount Sinai; Xinyii Hua, Georgia Southern University; Chigozie A Ogwara, Georgia Southern University; Margaret R Davies, Georgia Southern University; Temitayo M Adebile, Georgia Southern University; Maya P Sherman, Georgia Southern University; Xiaolu Zhou, Texas Christian University; Gerardo Chowell, Georgia State University; Anne Spaulding, Emory University; Isaac Chun-Hai Fung, Georgia Southern University
• Language: English
• Date: 2022-04-01
• Publisher: Elsevier Inc.
• Publication Version: Final Published Version
• Copyright Statement: © 2021 Elsevier Inc. All rights reserved.
• Final Published Version (URL): http://dx.doi.org/10.1016/j.annepidem.2021.12.012
• Title of Journal or Parent Work: Annals of Epidemiology
• Volume: 68
• Start Page: 37
• End Page: 44
• Keywords: Humans; Health Policy; Sars-cov-2; Population Density; Kentucky; COVID-19; Reproduction; Arkansas; Covid-19; Rural, policy; Reproduction number; SARS-CoV-2
• Research Categories: Health Sciences, Medicine and Surgery; Health Sciences, Epidemiology

Abstract

Purpose: To examine the time-varying reproduction number, Rt, for COVID-19 in Arkansas and Kentucky and investigate the impact of policies and preventative measures on the variability in Rt. Methods: Arkansas and Kentucky county-level COVID-19 cumulative case count data (March 6-November 7, 2020) were obtained. Rt was estimated using the R package ‘EpiEstim’, by county, region (Delta, non-Delta, Appalachian, non-Appalachian), and policy measures. Results: The Rt was initially high, falling below 1 in May or June depending on the region, before stabilizing around 1 in the later months. The median Rt for Arkansas and Kentucky at the end of the study were 1.15 (95% credible interval [CrI], 1.13, 1.18) and 1.10 (95% CrI, 1.08, 1.12), respectively, and remained above 1 for the non-Appalachian region. Rt decreased when facial coverings were mandated, changing by -10.64% (95% CrI, -10.60%, -10.70%) in Arkansas and -5.93% (95% CrI, -4.31%, -7.65%) in Kentucky. The trends in Rt estimates were mostly associated with the implementation and relaxation of social distancing measures. Conclusions: Arkansas and Kentucky maintained a median Rt above 1 during the entire study period. Changes in Rt estimates allow quantitative estimates of potential impact of policies such as facemask mandate.