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. 2023 Nov:87:9-16.
doi: 10.1016/j.annepidem.2023.09.006. Epub 2023 Sep 22.

Space-time clustering of COVID-19 cases in the United States veteran population

Danielle M Richard  1 , Julie A Gazmararian  2 , Alyssa Greenhouse  2 , Anjali Khakharia  3 , Lawrence S Phillips  4 , Lance A Waller  5
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Free article

Space-time clustering of COVID-19 cases in the United States veteran population

Danielle M Richard et al. Ann Epidemiol. 2023 Nov.
Free article

Abstract

Purpose: To assess the distribution and clustering of coronavirus disease 2019 (COVID-19) testing and incidence over space and time, U.S. Department of Veteran's Affairs (VA) data were used to describe where and when veterans experienced highest proportions of test positivity.

Methods: Data for 6,342,455 veterans who utilized VA services between January 1, 2018, and September 30, 2021, were assessed for COVID-19 testing and test positivity. Testing and positivity proportions by county were mapped and focused-cluster tests identified significant clustering around VA facilities. Spatial cluster analysis also identified where and when veterans experienced highest proportions of test positivity.

Results: Within the veterans study population and our time window, 21.3% received at least one COVID-19 test, and 20.4% of those tested had at least one positive test. There was statistically significant clustering of testing around VA facilities, revealing regional variation in testing practices. Veterans experienced highest test positivity proportions between November 2020 and January 2021 in a cluster of states in the Midwest, compared to those who received testing outside of the identified cluster (RR: 3.45).

Conclusions: Findings reflect broad regional trends in COVID-19 positivity which can inform VA policy and resource allocation. Additional analysis is needed to understand patterns during Delta and Omicron variant periods.

Keywords: COVID-19; Healthcare disparities; Social determinants of health; Spatial analysis; United States; Veterans health.

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Conflict of interest statement

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Danielle M Richard reports financial support was provided by National Center for Advancing Translational Sciences. Alyssa Greenhouse reports financial support was provided by the National Center for Advancing Translational Sciences. Lawrence S. Phillips reports financial support was provided by Cystic Fibrosis Foundation and the National Institutes of Health. Lawrence S. Phillips reports a relationship with Janssen Pharmaceuticals Inc that includes board membership. Lawrence S. Phillips reports a relationship with Diasyst, Inc. that includes board membership and equity or stocks. Dr. Phillips declares that there is no duality of interest associated with this manuscript. With regard to potential conflicts of interest, Dr. Phillips has served on Scientific Advisory Boards for Janssen, and has or had research support from Merck, Pfizer, Eli Lilly, Novo Nordisk, Sanofi, PhaseBio, Roche, Abbvie, Vascular Pharmaceuticals, Janssen, Glaxo SmithKline, and the Cystic Fibrosis Foundation. Dr. Phillips is also a cofounder and Officer and Board member and stockholder for a company, Diasyst, Inc., which markets software aimed to help improve diabetes management.

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