Expansion of wastewater-based disease surveillance to improve health equity in California's Central Valley: sequential shifts in case-to-wastewater and hospitalization-to-wastewater ratios

• Type of Material: Article
• Authors: Krystin F Kadonsky, University of California Merced; Colleen C Naughton, University of California Merced; Mirjana Susa, University of California Davis; Rachel Olson, University of California Davis; Guadalupe L Singh, University of California Merced; Maria L Daza-Torres, University of California Davis; J. Cricelio Montesinos-Lopez, University of California Davis; Yury Elena Garcia, University of California Davis; Maftuna Gafurova, Eurofins Environm Testing US; Adam Gushgari, Eurofins Environm Testing US; John Cosgrove, Eurofins Environm Testing US; Bradley J White, Verily Life Sciences, South San Francisco; Alexandria B Boehm, Stanford University; Marlene K Wolfe, Emory University; Miriam Nuño, University of California Davis; Heather N Bischel, University of California Davis
• Language: English
• Date: 2023-06-30
• Publisher: FRONTIERS MEDIA SA
• Publication Version: Final Published Version
• Copyright Statement: © 2023 Kadonsky, Naughton, Susa, Olson, Singh, Daza-Torres, Montesinos-López, Garcia, Gafurova, Gushgari, Cosgrove, White, Boehm, Wolfe, Nuño and Bischel.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3389/fpubh.2023.1141097
• Title of Journal or Parent Work: FRONTIERS IN PUBLIC HEALTH
• Volume: 11
• Start Page: 1141097
• End Page: 1141097
• Grant/Funding Information: The analyses conducted through SCAN were supported by a gift from the CDC-Foundation to AB. Additional research support for HCVT was provided through a philanthropic gift to the University of California, Davis.
• Keywords: wastewater clinical case ratios; Public, Environmental & Occupational Health; COVID-19; SARS-CoV-2; Life Sciences & Biomedicine; Science & Technology; health metrics; environmental surveillance
• Research Categories: Health Sciences, Public Health; Engineering, Environmental; Engineering, Civil

Abstract

Introduction: Over a third of the communities (39%) in the Central Valley of California, a richly diverse and important agricultural region, are classified as disadvantaged—with inadequate access to healthcare, lower socio-economic status, and higher exposure to air and water pollution. The majority of racial and ethnic minorities are also at higher risk of COVID-19 infection, hospitalization, and death according to the Centers for Disease Control and Prevention. Healthy Central Valley Together established a wastewater-based disease surveillance (WDS) program that aims to achieve greater health equity in the region through partnership with Central Valley communities and the Sewer Coronavirus Alert Network. WDS offers a cost-effective strategy to monitor trends in SARS-CoV-2 community infection rates. Methods: In this study, we evaluated correlations between public health and wastewater data (represented as SARS-CoV-2 target gene copies normalized by pepper mild mottle virus target gene copies) collected for three Central Valley communities over two periods of COVID-19 infection waves between October 2021 and September 2022. Public health data included clinical case counts at county and sewershed scales as well as COVID-19 hospitalization and intensive care unit admissions. Lag-adjusted hospitalization:wastewater ratios were also evaluated as a retrospective metric of disease severity and corollary to hospitalization:case ratios. Results: Consistent with other studies, strong correlations were found between wastewater and public health data. However, a significant reduction in case:wastewater ratios was observed for all three communities from the first to the second wave of infections, decreasing from an average of 4.7 ± 1.4 over the first infection wave to 0.8 ± 0.4 over the second. Discussion: The decline in case:wastewater ratios was likely due to reduced clinical testing availability and test seeking behavior, highlighting how WDS can fill data gaps associated with under-reporting of cases. Overall, the hospitalization:wastewater ratios remained more stable through the two waves of infections, averaging 0.5 ± 0.3 and 0.3 ± 0.4 over the first and second waves, respectively.