  Epidemic disease can spread during mass gatherings. We assessed the impact on
the local-area trajectory of the COVID-19 epidemic of a type of mass gathering
about which comprehensive data were available. Here, we examined five types of
political events in 2020 and 2021: the US primary elections; the US Senate
special election in Georgia; the gubernatorial elections in New Jersey and
Virginia; Donald Trump's political rallies; and the Black Lives Matter
protests. Our study period encompassed over 700 such mass gatherings during
multiple phases of the pandemic. We used data from the 48 contiguous states,
representing 3,119 counties, and we implemented a novel extension of a recently
developed non-parametric, generalized difference-in-difference estimator with a
(high-quality) matching procedure for panel data to estimate the average effect
of the gatherings on local mortality and other outcomes. There were no
statistically significant increases in cases, deaths, or a measure of epidemic
transmissibility (Rt) in a 40-day period following large-scale political
activities. We estimated small and statistically insignificant effects,
corresponding to an average difference of -0.0567 deaths (95% CI = -0.319,
0.162), and 8.275 cases (95% CI = -1.383, 20.7), on each day, for counties that
held mass gatherings for political expression compared to matched control
counties. In sum, there is no statistical evidence of a material increase in
local COVID-19 deaths, cases, or transmissibility after mass gatherings for
political expression during the first two years of the pandemic in the USA.
This may relate to the specific manner in which such activities are typically
conducted.
