Cited by 12Mathematical and Theoretical Epidemiology and Ecology ModelsCOVID-19 epidemiological studiesComplex Network Analysis Techniques

Understanding Nash epidemics

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Schnyder, Simon K., Molina, John J., Yamamoto, Ryoichi, Turner, Matthew S.·2025·Proceedings of the National Academy of Sciences

Abstract

Faced with a dangerous epidemic humans will spontaneously social distance to reduce their risk of infection at a socioeconomic cost. Compartmentalized epidemic models have been extended to include this endogenous decision making: Individuals choose their behavior to optimize a utility function, self-consistently giving rise to population behavior. Here, we study the properties of the resulting Nash equilibria, in which no member of the population can gain an advantage by unilaterally adopting different behavior. We leverage an analytic solution that yields fully time-dependent rational population behavior to obtain, 1) a simple relationship between rational social distancing behavior and the current number of infections; 2) scaling results for how the infection peak and number of total cases depend on the cost of contracting the disease; 3) characteristic infection costs that divide regimes of strong and weak behavioral response; 4) a closed form expression for the value of the utility. We discuss how these analytic results provide a deep and intuitive understanding of the disease dynamics, useful for both individuals and policymakers. In particular, the relationship between social distancing and infections represents a heuristic that could be communicated to the population to encourage, or “bootstrap,” rational behavior.

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  • A cFFL consists of a fast direct pathway and a slow indirect pathway, which filters out short-lived and spurious signals by integrating these inputs.

    “A cFFL consists of a fast direct pathway and a slow indirect pathway, which filters out short-lived and spurious signals by integrating these inputs.”

    From Theoretical Analysis of Resource-Induced Phase Transitions in Estimation Strategies (2026) · cites this paper as [46]

    The Results section discusses Nash-equilibrium social distancing and epidemic dynamics, not coherent feed-forward loops. Searches for “cFFL,” fast and slow pathways, and signal filtering found no passage in our copy addressing the claim. (LLM, conf=0.78)

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Research works printed but not linked: 2

  1. F. Toxvaerd R. Rowthorn “On the management of population immunity” (Cambridge Working Papers in Economics 2080 University of Cambridge 2020).
  2. F. Toxvaerd “Equilibrium social distancing” (Cambridge Working Papers in Economics 8(i)27 2020).

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Authors
Schnyder, S. K., Molina, J. J., Yamamoto, R., & Turner, M. S.
Affiliations
  • Institute of Industrial Science, The University of Tokyo (JP)
  • Kyoto University (JP)
  • Department of Chemical Engineering
  • University of Warwick (GB)
Corresponding author
  • Schnyder, Simon K.
  • Turner, Matthew S.
Venue
Proceedings of the National Academy of Sciences
Published
2025-02-27
Volume
122
Issue
9
Pages
e2409362122-e2409362122
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W4408019161
Cited by
12
References
92
Citations by year
2026: 6 · 2025: 6
FWCI
10.99
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • Warwick Research Archive Portal (University of Warwick) (acceptedVersion)
Funders
  • Japan Society for the Promotion of Science London (20H00129, 20H05619, 22H04841, 22K14012, 23H04508, JPJSCCA20230002, L19547)
  • Leverhulme Trust (IAF-2019-019)
Topics
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Mathematical and Theoretical Epidemiology and Ecology Models
  • Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
  • Physical Sciences › Physics and Astronomy › Statistical and Nonlinear Physics › Complex Network Analysis Techniques
Keywords
Nash equilibrium, epidemic dynamics, social distancing, rational choice, compartmental epidemic model, utility maximization, infection peak, analytical solution, epidemic control policy
MeSH terms
Physical Distancing, COVID-19, Humans, Epidemics

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