Study finds substantial undetected COVID-19 infections, inadequate testing among jail populations

This report is written by the Covid In-Custody Project which partners with the Davis Vanguard to bring reporting on the pandemic in California’s county jails and Department of Corrections and Rehabilitation (CDCR) to the public eye. Visit our website to view and download our data on cases, testing, releases and vaccinations for incarcerated people and staff. 

By Cassie Gorman

The incarcerated population in the United States has been disproportionately impacted by COVID-19. For example, nearly half of California state prisons had three to four times more COVID-19 cases than the general population. However, known figures may be underestimated, as a recent Stanford University study published in Frontiers in June of 2022 showed that the infection rate behind bars may significantly exceed the reported number of cases. 

From July 2020 to April 2021, 788 incarcerated individuals and 380 staff members were recruited from four jails in San Mateo and Santa Clara counties to participate in a study that involved COVID-19 antibody testing and a self-report questionnaire. 

The antibody testing identified whether a person had been infected with COVID-19, and the questionnaire asked about environmental factors that could increase the likelihood of infection. Participants’ test results and questionnaire responses were used to identify undetected or unreported infections. To our knowledge, this study is the first to employ antibody testing in an American carceral setting.

The results indicate a significant possible undercount of COVID-19 cases. 13% of the incarcerated people in the study were antibody-positive, yet half of them had not reported a positive COVID-19 test during their incarceration. Similarly, 8% of staff in the study were antibody-positive, and a third of them had not reported a positive test. 

The questionnaire responses revealed several potential contributors to this discrepancy, including reluctance to report symptoms to jail staff and insufficient testing.

A third of incarcerated people in the study who had flu-like symptoms did not report their symptoms to a nurse or doctor in the jail. The primary reason they cited was that they felt it was not a serious enough concern, and a significant portion cited concerns about being placed in isolation or being neglected or treated poorly by jail staff, as seen in the table below, published in the study.

Background: Carceral facilities are high-risk settings for COVID-19 transmission.

Yiran E Liu, a co-author of the paper, spoke with the Covid In-Custody Project about her work on the study, noting that she observed a widespread concern among the incarcerated population that testing positive for COVID-19 would lead to solitary confinement and unfavorable conditions. She believes that this likely deterred symptom reporting.

Additionally, 27.7% of respondents who did not report their symptoms cited a belief that nothing would be done to assist them. The responses to the questionnaire demonstrate that this belief is not unfounded, as over one-fifth of those who reported their symptoms to staff stated that no action was taken to administer testing or provide medical care. 

While the undercounting of positive cases is a critical issue, it is also important to examine why the infection rates in carceral settings are high. Yiran and her team found that limited access to face masks and overcrowded conditions have direct impacts on antibody positivity rates. Meaning, those who did not have access to clean masks or resided in overcrowded cells were more likely to contract COVID-19. 

The study found that those who received at least one new mask per week had an antibody positivity rate of 1.9%, while those who received less than one mask per month had an antibody positivity rate of 18.4%.  But unfortunately, 75% of respondents incarcerated for at least 30 days reported receiving a new face mask less than once a month, with almost 50% of them revealing that they had only received one mask since the pandemic began. 

Increased number of cell mates was also found to be associated with higher risk of antibody positivity, as those with eight or more cell mates had an antibody positivity rate of 25.3%, while those with zero to seven cellmates had an antibody positivity rate under 10%.

While antibody testing can detect whether a person has been infected with COVID-19, it cannot distinguish whether an infection occurred before an individual entered the jail. Antibodies remain in a person’s blood after they recover from the illness, so it is unknown whether a portion of those who tested positive for antibodies had COVID-19 before living or working in the jail.

Liu acknowledges this as a limitation of the study, but she believes some of the data makes it more likely that the antibodies detected are from infections that occurred in jail. 

“Antibody positivity did not significantly differ by the length of time incarcerated, including among people who were incarcerated for over six months prior to participating in our study — a time period over which we might expect antibodies from infection to wane considerably,” Liu notes.  

She also points to the fact that a majority of incarcerated people in the study who were antibody positive and had a sickness inside or outside of jail experienced a flu-like illness while in jail, and it is possible that in-custody illness could have been COVID-19.

This study adds valuable insight to what is known about COVID-19 in carceral settings, both from a preventative standpoint and in evaluating the consequences of the virus in prisons and jails. This includes the extent to which incarcerated people are negatively affected by so-called health and safety measures like medical isolation, restricted recreational time and suspended in-person visits and programming. 

“One theme that really emerged was how widespread reports of worse mental health were by folks in jail and how powerless they felt to protect their own health while incarcerated,” Liu says. “That was an angle that we started the study not expecting to focus on, but was prevalent.”

By utilizing incarcerated narratives in their report, these Stanford researchers have expanded an area of study that focuses not just on infection rates, but also the experiences of incarcerated individuals. Listening to human accounts brings both researchers and the general population closer to understanding how carceral policy and culture can worsen the impact of already harmful situations. 

“I think that we already have a lot of information from reporters, researchers and incarcerated people about what the problems are and what’s needed to change them and to mitigate the risk of COVID,” Liu says. “I would say the burden is on jail officials and policymakers to put those changes into action.”

About The Author

The Covid In-Custody Project partners with the Davis Vanguard to report on the pandemic's impact on California's county jails and state prisons. See for more information.

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