Projections of wastewater as an indicator of COVID-19 cases in corrections facilities: a modelling study

Background Although prison facilities are not fully isolated from the communities they are located within, the majority of the population is confined and requires high levels of health vigilance and protection. This study sought to examine the dynamic relationship between facility level wastewater viral RNA concentration and probability of at least one positive COVID-19 case within the facility. Methods The study period was January 11, 2021 through May 12, 2023. Wastewater samples were collected and analyzed for SARS-CoV-2 (N1) and pepper mild mottle virus (PMMoV) three times per week across 14 prison facilities in Kentucky (USA). Confirmed positive clinical case reports were also provided. A hierarchical Bayesian spatial-temporal model with a latent lagged process was developed. Findings We modeled a facility-specific SARS-CoV-2 (N1) normalized by PMMoV wastewater ratio associated with at least one COVID-19 facility case with an 80% probability. The ratio differs among facilities. Across the 14 facilities, our model demonstrates an average capture rate of 94·95% via the N1/PMMoV threshold with p ts ≥ 0·5. However, it is noteworthy as the p ts threshold is set higher, such as at 0·9 or above, the model’s average capture rate reduces to 60%. This robust performance underscores the model’s effectiveness in accurately detecting the presence of positive COVID-19 cases of incarcerated people. Interpretation The findings of this study provide a correction facility-specific threshold model for public health response based on frequent wastewater surveillance. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was funded by the Commonwealth of Kentucky Department of Corrections Contracts PON2 527 2200001913 1 and PON2 527 2100001185. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The University of Louisville Institutional Review Board classified this project as Non-Human Subject Research (reference #: 714006).   I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The computer code that implemented our model-based analysis will be made available immediately after publication.