Study population and setting
A medium security jail in Louisiana, with capacity for 800 people across 6 dormitories (A through F) operated at roughly 85% capacity due to COVID-19-related decarceration for infection control at the study start May 7, 2020. When individuals tested positive, they were removed to medical isolation, and the rest of the dormitory was quarantined together. As part of the study, on day 0, all individuals in dorms A to F were tested using nasopharyngeal swabs and real-time RT-PCR testing. They also received a baseline survey of symptoms in the prior 2 months and 2 weeks, potential facility exposures, any preventative measures taken, and demographic questions. Medical history was abstracted from medical records. Among those who tested negative on day 0, additional testing and an abridged questionnaire were completed on day 4, and (if still negative) day 14. To assess viral shedding, among those who did test positive on days 0, 4 or 14, they received testing at days 14 or 15 and days 19 or 27. No individuals tested positive in dorm F on day 0, and they were not offered serial testing until day 18 as well as a second survey. Lab testing also analyzed specimens for replication-competent viruses, which was considered a positive culture, and extracted nucleic acid and generated phylogenetic relations between strains.
Summary of Main Findings
Of the 143 detained people enrolled in the study across the 6 dormitories, all consented to participate and be tested on day 0. Most participants were non-Hispanic Black (N=102, 71%) and the majority were male (N=136, 95%). In dorms A-E, 54% (N=53/98) of people tested positive at baseline. Among the 45 participants with negative results in A-E, 16 (36%) tested positive on day 4. Of those 29 remaining negative on day 4, an additional 2 tested positive on day 14 (6.9%). While no one tested positive in dorm F on day 0, by day 18, 89% (40 of 45 individuals) tested positive. In total, 111 people (77.6%) of detained people tested positive during the study, 21 (19%) of whom were symptomatic at the time of their positive test, while 24% (N=27) reported symptoms had resolved before their positive test. 11 cases did not report their symptoms, and among the 51 symptomatic cases (46%), positive rRT-PCR results were obtained with a range of 7 days before symptom onset to 48 days after symptom onset. 23% (N=25) of 110 samples tested had virus able to replicate in the lab. Replication-competent virus was not isolated from any specimen obtained >9 days from symptom onset. In their phylogenic analysis among samples from A, D, E, and F dorms, phylogenies grouped to 1 group in dorms D and E, a second group with D and A, and a third group only among people in dormitory F, all within clade 20C.
The study drew on a number of both epidemiological and laboratory assessments to build a comprehensive picture of symptom onset and viral transmission, using serial testing, viral culturing, and phylogenetic analysis. They were also able to obtain specimens in the pre-symptomatic, symptomatic, and post-symptomatic phases, giving some insight into the natural history of COVID-19 in a congregate setting with high rates of transmission. Additionally, because there was serial testing available after the introduction of SARS-Cov-2 into the facility, they were able to identify individuals early in their infectious period and mitigate transmission somewhat.
The notable limitation was that the testing-isolation strategy still resulted in a high cumulative incidence rate, highlighting the need for further infection control protocols in these settings beyond serial testing and isolation. Additionally, the interval between the first and second test for dorm F was 18 days, during which the infection spread from 0 to 40 individuals, of 45 total. They also did not test any staff, correctional officers, or persons in other dorms as part of their study, therefore it does not give a whole picture of viral transmission within the facility, and earlier detection may have been possible had these data been available. The study did not specify why only 143 people were tested in an 800-capacity facility, and how these dorms were selected. This may result in selection bias, and it is not possible to determine to what degree it may impact results. In a correctional setting, as well, there may be disincentives to report symptoms by individuals. Many jails lack medical isolation facilities and therefore have resorted to repurposing solitary confinement cells, which many incarcerated people fear being put in. The medical isolation protocols are not detailed in the study. There also was a high number of people reporting COVID-19 symptoms but who tested negative, which may mean their infection resolved before testing and these estimates may underestimate the prevalence, or that separate respiratory infections were spreading in the facility at the time.
This study is one of the most comprehensive investigations of transmission in prisons to date, drawing on both epidemiological investigations of COVID-19 and laboratory data and cultures.
This review was posted on: 28 January 2021