Correlation of SARS-CoV-2 in Wastewater and Individual Testing Results in a Jail, Atlanta, Georgia, USA

Abstract

Institution-level wastewater-based surveillance was implemented during the COVID-19 pandemic, including in carceral facilities. We examined the relationship between COVID-19 diagnostic test results of residents in a jail in Atlanta, Georgia, USA (average population ≈2,700), and quantitative reverse transcription PCR signal for SARS-CoV-2 in weekly wastewater samples collected during October 2021‒May 2022. The jail offered residents rapid antigen testing at entry and periodic mass screenings by reverse transcription PCR of self-collected nasal swab specimens. We aggregated individual test data, calculated the Spearman correlation coefficient, and performed logistic regression to examine the relationship between strength of SARS-CoV-2 PCR signal (cycle threshold value) in wastewater and percentage of jail population that tested positive for COVID-19. Of 13,745 nasal specimens collected, 3.9% were COVID-positive (range 0%-29.5% per week). We observed a strong inverse correlation between diagnostic test positivity and cycle threshold value (r = -0.67; p<0.01). Wastewater-based surveillance represents an effective strategy for jailwide surveillance of COVID-19.

Keywords: Atlanta; COVID-19; Georgia; SARS-CoV-2; United States; coronaviruses; correctional; epidemiology; jail; respiratory infections; virus detection method; viruses; wastewater-based surveillance; zoonoses.

Figure 1

Moore swab: 4-in by 4-in cotton gauze squares tied together with nylon fishing line (21).

Figure 2

Outline of the Fulton County Jail, Atlanta, Georgia, USA, showing wastewater-based surveillance collection sites. Site 3 was used for final analysis as a proxy for wastewater-based surveillance results of the entire jail.

Figure 3

Average Ct values of wastewater samples (black lines) versus total percentage of negative COVID-19 diagnostic test results (red lines), Fulton County Jail, Atlanta, Georgia, USA, October 2021‒May 2022. Dot sizes are proportional to the percentage of the jail population undergoing a COVID-19 diagnostic test for the corresponding week. Ct, cycle threshold.

Figure 4

PCR and rapid COVID-19 diagnostic test results, Fulton County, Jail, Atlanta, Georgia, USA, October 2021‒May 2022. The percentage of the combined negative diagnostic results is overlaid, showing peak in positive results (i.e., nadir of negative results) in late December 2021.