# Mass gatherings as natural experiments: travel pulses reveal determinants of SARS-CoV-2 epidemic synchrony and predictability in U.S. states and counties

> **NIH NIH R21** · UNIVERSITY OF GEORGIA · 2023 · $190,165

## Abstract

Project Summary
 Variation in epidemic timing and intensity among U.S. communities has exacerbated shortages of vital pub-
lic health resources, from testing and contact tracing to hospital beds and health care workers. Understanding
when and why communities are most vulnerable to epidemic disease remains a critical unmet need in this
and future epidemics. Our study will leverage a set of five mass gatherings (e.g., the Sturgis Motorcycle Ral-
lies in 2020 and 2021) to assess the variable impact of travel pulses across a spectrum of U.S. communities. Our
study is organized around two principle aims: Aim 1. To quantify how disease incidence in U.S. counties responds
to travel pulses from focal mass gatherings in 2020 and then identify predictors of differing responses. To achieve this,
we will use statistical models to quantify counties' differing response to travelers as a function of urbanicity,
geographic isolation, age structure, and economic status. Aim 2. To quantify how disease predictability and connec-
tivity vary among U.S. counties across 2020 and 2021. We will construct and parameterize mechanistic models of
county-level transmission, and then assess model forecasting skill over short-term time horizons. This research
will provide much-needed national and state summaries detailing which forces most strongly affect disease
connectivity and predictability. Our work will provide detailed evaluations of individual counties, including
publicly accessible interactive maps illustrating the relative effects of geography, demography, infection history,
and vaccination. These products will help stakeholders identify at-risk communities and tailor control efforts to
local conditions, and will highlight regions where increased surveillance is warranted.

## Key facts

- **NIH application ID:** 10632138
- **Project number:** 5R21AI171509-02
- **Recipient organization:** UNIVERSITY OF GEORGIA
- **Principal Investigator:** Pejman Rohani
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $190,165
- **Award type:** 5
- **Project period:** 2022-06-01 → 2026-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10632138

## Citation

> US National Institutes of Health, RePORTER application 10632138, Mass gatherings as natural experiments: travel pulses reveal determinants of SARS-CoV-2 epidemic synchrony and predictability in U.S. states and counties (5R21AI171509-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10632138. Licensed CC0.

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