Time series modelling for wastewater-based epidemiology of COVID-19: A nationwide study in 40 wastewater treatment plants of Belgium, February 2021 to June 2022

Xander Bertels; Sven Hanoteaux; Raphael Janssens; Hadrien Maloux; Bavo Verhaegen; Peter Delputte; Tim Boogaerts; Alexander L N van Nuijs; Delphine Brogna; Catherine Linard; Jonathan Marescaux; Christian Didy; Rosalie Pype; Nancy H C Roosens; Koenraad Van Hoorde; Marie Lesenfants; Lies Lahousse

doi:10.1016/j.scitotenv.2023.165603

Time series modelling for wastewater-based epidemiology of COVID-19: A nationwide study in 40 wastewater treatment plants of Belgium, February 2021 to June 2022

Sci Total Environ. 2023 Nov 15:899:165603. doi: 10.1016/j.scitotenv.2023.165603. Epub 2023 Jul 19.

Authors

Xander Bertels¹, Sven Hanoteaux², Raphael Janssens², Hadrien Maloux², Bavo Verhaegen³, Peter Delputte⁴, Tim Boogaerts⁵, Alexander L N van Nuijs⁵, Delphine Brogna⁶, Catherine Linard⁶, Jonathan Marescaux⁷, Christian Didy⁸, Rosalie Pype⁸, Nancy H C Roosens⁹, Koenraad Van Hoorde³, Marie Lesenfants², Lies Lahousse¹⁰

Affiliations

¹ Department of Bioanalysis, Ghent University, 9000 Ghent, Belgium.
² Epidemiology and Public Health, Epidemiology of Infectious Diseases, Sciensano, 1050 Brussels, Belgium.
³ Infectious Diseases in Humans, Foodborne Pathogens, Sciensano, 1050 Brussels, Belgium.
⁴ Laboratory for Microbiology, Parasitology and Hygiene, University of Antwerp, 2610 Wilrijk, Belgium.
⁵ Toxicological Centre, University of Antwerp, 2610 Antwerp, Belgium.
⁶ Institute of Life, Earth and Environment, University of Namur, 5000 Namur, Belgium.
⁷ Institute of Life, Earth and Environment, University of Namur, 5000 Namur, Belgium; E-BIOM SA, 5000 Namur, Belgium.
⁸ Société Publique de Gestion de l'Eau, 4800 Verviers, Belgium.
⁹ Biological Health Risks, Transversal Activities in Applied Genomics, Sciensano, 1050 Brussels, Belgium.
¹⁰ Department of Bioanalysis, Ghent University, 9000 Ghent, Belgium. Electronic address: lies.lahousse@ugent.be.

PMID: 37474075
DOI: 10.1016/j.scitotenv.2023.165603

Abstract

Background: Wastewater-based epidemiology (WBE) has been implemented to monitor surges of COVID-19. Yet, multiple factors impede the usefulness of WBE and quantitative adjustment may be required.

Aim: We aimed to model the relationship between WBE data and incident COVID-19 cases, while adjusting for confounders and autocorrelation.

Methods: This nationwide WBE study includes data from 40 wastewater treatment plants (WWTPs) in Belgium (02/2021-06/2022). We applied ARIMA-based modelling to assess the effect of daily flow rate, pepper mild mottle virus (PMMoV) concentration, a measure of human faeces in wastewater, and variants (alpha, delta, and omicron strains) on SARS-CoV-2 RNA levels in wastewater. Secondly, adjusted WBE metrics at different lag times were used to predict incident COVID-19 cases. Model selection was based on AICc minimization.

Results: In 33/40 WWTPs, RNA levels were best explained by incident cases, flow rate, and PMMoV. Flow rate and PMMoV were associated with -13.0 % (95 % prediction interval: -26.1 to +0.2 %) and +13.0 % (95 % prediction interval: +5.1 to +21.0 %) change in RNA levels per SD increase, respectively. In 38/40 WWTPs, variants did not explain variability in RNA levels independent of cases. Furthermore, our study shows that RNA levels can lead incident cases by at least one week in 15/40 WWTPs. The median population size of leading WWTPs was 85.1 % larger than that of non‑leading WWTPs. In 17/40 WWTPs, however, RNA levels did not lead or explain incident cases in addition to autocorrelation.

Conclusion: This study provides quantitative insights into key determinants of WBE, including the effects of wastewater flow rate, PMMoV, and variants. Substantial inter-WWTP variability was observed in terms of explaining incident cases. These findings are of practical importance to WBE practitioners and show that the early-warning potential of WBE is WWTP-specific and needs validation.

Keywords: ARIMA; COVID-19; Flow rate; PMMoV; Wastewater surveillance.

MeSH terms

Belgium / epidemiology
COVID-19* / epidemiology
Humans
RNA, Viral*
SARS-CoV-2
Time Factors
Wastewater
Wastewater-Based Epidemiological Monitoring

Substances

RNA, Viral
Wastewater

Supplementary concepts

Pepper mild mottle virus