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Epidemiology of SARS-CoV-2 transmission and superspreading in Salt Lake County, Utah, March-May 2020.

Authors :
Walker J
Tran T
Lappe B
Gastanaduy P
Paul P
Kracalik IT
Fields VL
Lopez A
Schwartz A
Lewis NM
Tate JE
Kirking HL
Hall AJ
Pevzner E
Khong H
Smithee M
Lowry J
Dunn A
Kiphibane T
Tran CH
Source :
PloS one [PLoS One] 2023 Jun 23; Vol. 18 (6), pp. e0275125. Date of Electronic Publication: 2023 Jun 23 (Print Publication: 2023).
Publication Year :
2023

Abstract

Background: Understanding the drivers of SARS-CoV-2 transmission can inform the development of interventions. We evaluated transmission identified by contact tracing investigations between March-May 2020 in Salt Lake County, Utah, to quantify the impact of this intervention and identify risk factors for transmission.<br />Methods: RT-PCR positive and untested symptomatic contacts were classified as confirmed and probable secondary case-patients, respectively. We compared the number of case-patients and close contacts generated by different groups, and used logistic regression to evaluate factors associated with transmission.<br />Results: Data were collected on 184 index case-patients and up to six generations of contacts. Of 1,499 close contacts, 374 (25%) were classified as secondary case-patients. Decreased transmission odds were observed for contacts aged <18 years (OR = 0.55 [95% CI: 0.38-0.79]), versus 18-44 years, and for workplace (OR = 0.36 [95% CI: 0.23-0.55]) and social (OR = 0.44 [95% CI: 0.28-0.66]) contacts, versus household contacts. Higher transmission odds were observed for case-patient's spouses than other household contacts (OR = 2.25 [95% CI: 1.52-3.35]). Compared to index case-patients identified in the community, secondary case-patients identified through contract-tracing generated significantly fewer close contacts and secondary case-patients of their own. Transmission was heterogeneous, with 41% of index case-patients generating 81% of directly-linked secondary case-patients.<br />Conclusions: Given sufficient resources and complementary public health measures, contact tracing can contain known chains of SARS-CoV-2 transmission. Transmission is associated with age and exposure setting, and can be highly variable, with a few infections generating a disproportionately high share of onward transmission.<br />Competing Interests: The authors have declared that no competing interests exist.<br /> (Copyright: This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.)

Details

Language :
English
ISSN :
1932-6203
Volume :
18
Issue :
6
Database :
MEDLINE
Journal :
PloS one
Publication Type :
Academic Journal
Accession number :
37352280
Full Text :
https://doi.org/10.1371/journal.pone.0275125