Results from the SARS-CoV-2 wastewater-based surveillance system in Denmark, July 2021 to June 2022

Research output: Contribution to journalJournal articleResearchpeer-review


  • Fulltext

    Final published version, 1.46 MB, PDF document

  • Lene Wulff Krogsgaard
  • Aina Gudde
  • Stine Raith Richter
  • Lasse Dam Rasmussen
  • Sofie Elisabeth Midgley
  • Amanda Gammelby Qvesel
  • Maarten Nauta
  • Naja Stolberg Bahrenscheer
  • Lene von Kappelgaard
  • Oliver McManus
  • Nicco Claudio Hansen
  • Jan Bryla Pedersen
  • Danny Haimes
  • Jesper Gamst
  • Louise Solveig Nørgaard
  • Alissa Carina Udi Jørgensen
  • Ditte Møller Ejegod
  • Simone Skjødt Møller
  • Jes Clauson-Kaas
  • Ida Marie Knudsen
  • Kristina Træholt Franck

The microbiological analysis of wastewater samples is increasingly used for the surveillance of SARS-CoV-2 globally. We described the setup process of the national SARS-CoV-2 wastewater-based surveillance system in Denmark, presented its main results during the first year of activities, from July 2021 to June 2022, and discussed their operational significance. The Danish SARS-CoV-2 wastewater-based surveillance system was designed to cover 85 % of the population in Denmark and it entailed taking three weekly samples from 230 sites. Samples were RT-qPCR tested for SARS-CoV-2 RNA, targeting the genetic markers N1, N2 and RdRp, and for two faecal indicators, Pepper Mild Mottle Virus and crAssphage. We calculated the weekly SARS-CoV-2 RNA concentration in the wastewater from each sampling site and monitored it in view of the results from individual testing, at the national and regional levels. We attempted to use wastewater results to identify potential local outbreaks, and we sequenced positive wastewater samples using Nanopore sequencing to monitor the circulation of viral variants in Denmark. The system reached its full implementation by October 2021 and covered up to 86.4 % of the Danish population. The system allowed for monitoring of the national and regional trends of SARS-CoV-2 infections in Denmark. However, the system contribution to the identification of potential local outbreaks was limited by the extensive information available from clinical testing. The sequencing of wastewater samples identified relevant variants of concern, in line with results from sequencing of human samples. Amidst the COVID-19 pandemic, Denmark implemented a nationwide SARS-CoV-2 wastewater-based surveillance system that integrated routine surveillance from individual testing. Today, while testing for COVID-19 at the community level has been discontinued, the system is on the frontline to monitor the occurrence and spread of SARS-CoV-2 in Denmark.

Original languageEnglish
JournalWater Research
Pages (from-to)121223
Number of pages9
Publication statusPublished - 2024

Bibliographical note

Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.

    Research areas

  • Humans, SARS-CoV-2/genetics, COVID-19/epidemiology, COVID-19 Testing, Pandemics, RNA, Viral, Wastewater, Wastewater-Based Epidemiological Monitoring, Denmark/epidemiology

ID: 386144594