A wastewater-based epidemiology tool for COVID-19 surveillance in Portugal

Abstract

The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater produced interest in its use for sentinel surveillance at a community level and as a complementary approach to syndromic surveillance. With this work, we set the foundations for wastewater-based epidemiology (WBE) in Portugal by monitoring the trends of SARS-CoV-2 RNA circulation in the community, on a nationwide perspective during different epidemiological phases of the pandemic. The Charité assays (E_Sarbecco, RdRP, and N_Sarbecco) were applied to monitor, over 32-weeks (April to December 2020), the dynamics of SARS-CoV-2 RNA at the inlet of five wastewater treatment plants (WWTP), which together serve more than two million people in Portugal. Raw wastewater from three Coronavirus disease 2019 (COVID-19) reference hospitals was also analyzed during this period. In total, more than 600 samples were tested. For the first weeks, detection of SARS-CoV-2 RNA was sporadic, with concentrations varying from 10 3 to 10 5 genome copies per liter (GC/L). Prevalence of SARS-CoV-2 RNA increased steeply by the end of May into late June, mainly in Lisboa e Vale do Tejo region (LVT), during the reopening phase. After the summer, with the reopening of schools in mid-September and return to partial face-to-face work, a pronounced increase of SARS-CoV-2 RNA in wastewater was detected. In the LVT area, SARS-CoV-2 RNA load agreed with reported trends in hotspots of infection. Synchrony between trends of SARS-CoV-2 RNA in raw wastewater and daily new COVID-19 cases highlights the value of WBE as a surveillance tool, particularly after the phasing out of the epidemiological curve and when hotspots of disease re-emerge in the population which might be difficult to spot based solely on syndromic surveillance and contact tracing. This is the first study crossing several epidemiological stages highlighting the long-term use of WBE for SARS-CoV-2.

Wastewater-based epidemiology for early warning of SARS-COV-2 circulation: A pilot study conducted in Sicily, Italy

“…Today, we know that human pathogens in wastewater can represent a good proxy of the concentrations excreted by the population afferent to the treatment plant if they persist long enough (2–4 days) to be detected ( Brouwer et al, 2018 ; Carducci et al, 2020 ; Kitajima et al, 2020 ). Therefore, monitoring temporal changes in viral concentrations and diversity in community wastewater samples can be used not only to determine the true extent of the infection in the population but also the emergence of new viral strains and the early detection of new viral outbreaks ( Ahmed et al, 2020 ; Daughton, 2012 ; Johnson et al, 2021 ; Hart and Halden, 2020 ; La Rosa et al, 2021b ; Monteiro et al, 2022 ). While retrospective studies have already demonstrated the feasibility as an alert system, WBE for real-time early warning cannot be realized without frequent sampling, rapid sample delivery, analytical turnaround, and reporting.…”

SARS-CoV-2 RNA in Wastewater Was Highly Correlated With the Number of COVID-19 Cases During the Fourth and Fifth Pandemic Wave in Kobe City, Japan

“…Rainfall was expected to have little effect on RNA concentrations as no inverse correlation between amount of rainfall/influent flow and SARS-CoV-2 RNA in solid was observed. Previous studies showed that composite samples, which were collected by flow-weighting for 24 h, were more detectable than grab samples for SARS-CoV-2 RNA in wastewater ( Gerrity et al, 2021 ; Monteiro et al, 2022 ). However, grab sampling had been performed for SARS-CoV-2 RNA detection ( Randazzo et al, 2020 ; Carrillo-Reyes et al, 2021 ; Kitamura et al, 2021 ; Street et al, 2021 ; Wehrendt et al, 2021 ), and correlated with COVID-19 cases ( Kitamura et al, 2021 ; Street et al, 2021 ).…”

“…Monitoring the prevalence of SARS-CoV-2 in wastewater is also considered to be an effective approach for predicting the COVID-19 epidemic following the detection of SARS-CoV-2 RNA in sewage in several countries ( Ahmed et al, 2020a ; La Rosa et al, 2020b ; Wang et al, 2020 ; Wurtzer et al, 2020 , 2022 ; Albastaki et al, 2021 ; Wehrendt et al, 2021 ; Kevill et al, 2022 ). In some of these studies, the RNA copy number of SARS-CoV-2 in the sewage was correlated with the number of COVID-19 clinical cases ( Medema et al, 2020a ; Carrillo-Reyes et al, 2021 ; Nagarkar et al, 2021 ; Street et al, 2021 ; Wurtz et al, 2021 ; Monteiro et al, 2022 ). In Japan, SARS-CoV-2 RNA was first detected in secondary treated wastewater before chlorination at a WWTP in Yamanashi Prefecture in April 2020 ( Haramoto et al, 2020 ).…”

National Scale Real-Time Surveillance of Sars-Cov-2 Variants Dynamics by Wastewater Monitoring in Israel

“…Previous reports were limited in the number of sites examined, and mostly used sequencing to identify the circulation of variants of interest 37,38 . A national-scale surveillance in Portugal was comprehensive, but was performed during 2020 and therefore did not examine variant identity 39 . While sequencing provides complete information on the examined sample, it is expensive, not readily amendable for high throughput, and is limited by the sample quality.…”