Prisons and COVID-19 Spread in the United States

Kaitlyn M. Sims, MSc; Jeremy Foltz, PhD; Marin Elisabeth Skidmore, PhD


Am J Public Health. 2021;111(8):1534-1541. 

In This Article


We found that the presence of a prison corresponded with a 9% increase in cases within the county. Cases increased with the capacity of the prison, and federal and state prisons were stronger correlates of case counts than local and county jails (hereafter, "jails"). We conclude that both the presence and scale of incarceration facilities matter for disease spread.

We calculated a back-of-the-envelope estimate of US COVID-19 cases associated with presence of prisons. In our data, there were 2 653 050 confirmed COVID-19 cases as of July 1, 2020. As we expected the effects of prisons to be particularly important for rural and suburban communities, we calculated these associated cases for each of the rural–urban classification groups. Using the coefficients from Figure 2, we found that 132 582 cases (4.9% of all cases as of July 1) were associated with prisons, with the greatest number of associated cases found in larger, more metropolitan areas. These numbers are smaller than those found in studies looking at the Sturgis Motorcycle Rally superspreader event (in August 2020[38] ) and at meat processors[15] but are still sizable and important. This is particularly true when we consider the opt-in nature of these large superspreader events, in contrast to the absence of choice that incarcerated individuals have in where they are incarcerated and how correctional facilities respond to transmission risk.

Next, we accounted for heterogeneity in the effect by urban–rural classification. Table K (available as a supplement to the online version of this article at uses the coefficients from 3 separate regressions of prisons on case counts, split by urban–rural classification (regression results are reported in Table J, available as a supplement to the online version of this article at Increases in prison capacity are correlated with increases in cases in all classifications. However, smaller counties have smaller capacity prisons, on average, and the dummy for prison presence is only significant in large, urban counties. Less than 1% of micropolitan or noncore cases are associated with prison presence, whereas the population share in large central or fringe counties is over 16%, or 300 903 cases.

Finally, we used the coefficient estimates from our main specification to conduct a back-of-the-envelope calculation of the number of spillover cases beyond those in prison outbreaks themselves. We collected state-level cumulative totals of the number of cases and deaths among incarcerated individuals and corrections officers and staff around July 1, 2020 (data collected by the Marshall Project[16]). (Some states did not report on exactly July 1, 2020, so data comes from June 28 to July 3.) We then compared the number of cases and deaths in prisons to the estimated cases associated with prisons to estimate the spillover of cases beyond 6 prison environments. We estimated a total spillover of 95 055 cases and 3336 deaths across all 50 states (excluding the District of Columbia, for which prison-specific case and death data were not available). We take this as suggestive evidence that the effects of prisons on COVID-19 transmission extends beyond cases and deaths among incarcerated individuals and corrections officers and staff.


Despite the significant results presented here, there are limitations when using data on COVID-19 case counts and deaths. Testing is inconsistent throughout the United States, and shortages of tests have made it difficult for individuals exhibiting symptoms to get tested.[39] This is exacerbated by the fact that asymptomatic carriers are often unlikely to be tested at all, making reported case counts a noisy proxy for the true level of cases.

Pertinent to our work, testing protocol in prisons varied significantly across states and facilities. In late April, some facilities began testing all incarcerated individuals, whereas others had stopped testing altogether.[40] We cannot rule out that the spike in cases we detected was influenced by large-scale testing in the prisons. However, we detected a significant increase in cases 30 days after outbreak onset, which is before the earliest reported mass testing in prison for the median county. Moreover, we found a difference up to 150 days after the outbreak onset, suggesting continued cases beyond an initial testing spike. Finally, our estimate of prison-related cases exceeds the actual number of cases in prisons, suggesting spread from prisons to the surrounding community.

Finally, we interpret our results as correlational evidence of the relationship between these facility types and COVID-19 spread, rather than causal evidence. Although the location decision for prisons should be exogenous to county-level spread, future work is needed to strengthen this causal link. As data become available, especially at an individual level, researchers may distinguish between the risk of prison presence and the risk of proximity to a prison.