Equity in Wastewater Surveillance: Assessment of the National Wastewater Surveillance System for COVID-19

Wastewater surveillance has been used for COVID-19 detection, allowing for real-time responses to outbreaks and supplementing clinical testing, especially for vulnerable and under-resourced populations. The authors assessed the demographic and place-based inclusivity of the U.S. COVID-19 wastewater surveillance infrastructure overall and as surveillance expanded during the pandemic.

The authors extracted data on U.S. counties represented by the National Wastewater Surveillance System between 2020 and 2024 from the Centers for Disease Control and Prevention and demographic and social determinants of health data from the American Community Survey. The authors used generalized linear mixed models with a logit link adjusted for population size and state as a random effect to examine whether race, public assistance, education, and disability status were associated with surveillance coverage. The authors also examined whether surveillance expansion was equitable by comparing the characteristics of initial versus widespread adopters using the Wilcoxon rank sum test.

Approximately 27% (n=859) of U.S. counties had COVID-19 wastewater surveillance. Each unit increase in a county's percentage of residents who were White (OR=1.36; 95% CI=1.10, 1.69) was associated with higher odds of surveillance. The authors found some evidence of increased equity in wastewater surveillance as it became widespread. However, counties with higher percentages of households receiving public assistance, disabled residents, and renter-occupied households were still unlikely to be included in wastewater surveillance efforts later in the pandemic.

Demographic characteristics associated with marginalization were associated with lower odds of wastewater surveillance, highlighting disparities in and opportunities for expanding surveillance coverage across the U.S.