Characterizing superspreading events and age-specific infectiousness of SARS-CoV-2 transmission in Georgia, USA

• Type of Material: Article
• Authors: Max Siu Y. Lau, Emory University; Bryan Grenfell, Princeton University; Michael Thomas, Georgia Department of Public Health; Michael Bryan, Georgia Department of Public Health; Kristin Nelson, Emory University; Benjamin Lopman, Emory University
• Language: English
• Date: 2020-09-08
• Publisher: NATL ACAD SCIENCES
• Publication Version: Final Published Version
• Copyright Statement: © 2020 the Author(s). Published by PNAS.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1073/pnas.2011802117
• Title of Journal or Parent Work: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• Volume: 117
• Issue: 36
• Start Page: 22430
• End Page: 22435
• Grant/Funding Information: B.L. and K.N. acknowledge support from NIH/ National Institute of General Medical Sciences (Grants R01 GM124280 and 3R01GM124280-03S1), NIH/National Institute of Allergy and Infectious Diseases (Grant 3R01AI143875-02S1), and NSF (Grant 2032084).
• Keywords: superspreading; age-specific infectiousness; Multidisciplinary Sciences; SARS-CoV-2; mobility data; Science & Technology; Science & Technology - Other Topics; social distancing
• Research Categories: Health Sciences, Public Health; Biology, Virology

Abstract

It is imperative to advance our understanding of heterogeneities in the transmission of SARS-CoV-2 such as age-specific infectiousness and superspreading. To this end, it is important to exploit multiple data streams that are becoming abundantly available during the pandemic. In this paper, we formulate an individual-level spatiotemporal mechanistic framework to integrate individual surveillance data with geolocation data and aggregate mobility data, enabling a more granular understanding of the transmission dynamics of SARS-CoV-2. We analyze reported cases, between March and early May 2020, in five (urban and rural) counties in the state of Georgia. First, our results show that the reproductive number reduced to below one in about 2 wk after the shelter-in-place order. Superspreading appears to be widespread across space and time, and it may have a particularly important role in driving the outbreak in rural areas and an increasing importance toward later stages of outbreaks in both urban and rural settings. Overall, about 2% of cases were directly responsible for 20% of all infections. We estimate that the infected nonelderly cases (<60 y) may be 2.78 [2.10, 4.22] times more infectious than the elderly, and the former tend to be the main driver of superspreading. Our results improve our understanding of the natural history and transmission dynamics of SARS-CoV-2. More importantly, we reveal the roles of age-specific infectiousness and characterize systematic variations and associated risk factors of superspreading. These have important implications for the planning of relaxing social distancing and, more generally, designing optimal control measures.