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

• Published in: The Science of the total environment 2022-01, Vol.804, p.150264-150264, Article 150264
• Main Authors: Monteiro, Sílvia, Rente, Daniela, Cunha, Mónica V., Gomes, Manuel Carmo, Marques, Tiago A., Lourenço, Artur B., Cardoso, Eugénia, Álvaro, Pedro, Silva, Marco, Coelho, Norberta, Vilaça, João, Meireles, Fátima, Brôco, Nuno, Carvalho, Marta, Santos, Ricardo
• Format: Article
• Language: English
• Subjects: COVID-19; Hospital wastewater; Humans; Portugal - epidemiology; RNA, Viral; SARS-CoV-2; Wastewater; Wastewater-Based Epidemiological Monitoring; Wastewater-based epidemiology
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.150264

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 103 to 105 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. [Display omitted] •SARS-CoV-2 monitored over 32-weeks encompassing different epidemiological stages.•Five wastewater treatment plants, representing over two million people, were tested.•Trends of SARS-CoV-2 in wastewater followed trends of daily new cases in Portugal.•Sampling strategy may have a marked impact in the detection of SARS-CoV-2.•Long-term potential of WBE as a complementary tool to clinical surveillance demonstrated.