Background: During the COVID-19 pandemic, wastewater-based surveillance gained great international interest as an additional tool to monitor SARS-CoV-2. In autumn 2021, the Norwegian Institute of Public Health decided to pilot a national wastewater surveillance (WS) system for SARS-CoV-2 and its variants between June 2022 and March 2023. We evaluated the system to assess if it met its objectives and its attribute-based performance. Methods: We adapted the available guidelines for evaluation of surveillance systems. The evaluation was carried out as a descriptive analysis and consisted of the following three steps: (i) description of the WS system, (ii) identification of users and stakeholders, and (iii) analysis of the system attributes and performance including sensitivity, specificity, timeliness, usefulness, representativeness, simplicity, flexibility, stability, and communication. Cross-correlation analysis was performed to assess the system ability to provide early warning signal of new wave of infections. Results: The pilot WS system was a national surveillance system using existing wastewater infrastructures from the largest Norwegian municipalities. We found that the system was sensitive, timely, useful, representative, simple, flexible, acceptable, and stable to follow the general trend of infection. Preliminary results indicate that the system could provide an early signal of changes in variant distribution. However, challenges may arise with: (i) specificity due to temporary fluctuations of RNA levels in wastewater, (ii) representativeness when downscaling, and (iii) flexibility and acceptability when upscaling the system due to limited resources and/or capacity. Conclusions: Our results showed that the pilot WS system met most of its surveillance objectives. The system was able to provide an early warning signal of 1-2 weeks, and the system was useful to monitor infections at population level and complement routine surveillance when individual testing activity was low. However, temporary fluctuations of WS values need to be carefully interpreted. To improve quality and efficiency, we recommend to standardise and validate methods for assessing trends of new waves of infection and variants, evaluate the WS system using a longer operational period particularly for new variants, and conduct prevalence studies in the population to calibrate the system and improve data interpretation.

Background: To allow for normal school attendance during the COVID-19 pandemic, regular testing of students was introduced in the autumn 2021 in Norway to manage COVID-19 transmission. We mapped the experiences of five stakeholders (parents, students, school staff and administration, contact tracing teams) regarding the implementation of regular testing in primary and secondary schools in Oslo and Viken counties, to assess the acceptability through different indicators and improve future guidelines. Methods: A cross-sectional survey was conducted between October and November 2021 to explore experiences of implementation, compliance, satisfaction, difficulties, concerns, confidence in regular testing, quality of teaching and school attendance. Five stakeholder groups were invited to participate: contact tracing teams; school administrators and employees in primary, lower secondary, and upper-secondary school; students in upper-secondary school and parents of primary and lower secondary students. Bivariate analyses were performed for students, parents, and school employees groups. Descriptive analyses were done for contact tracing teams and school administrators. Results: 4 576 participants completed the survey. School attendance increased for most of the students in primary and lower secondary schools in Oslo and Viken after the implementation of regular testing. Students across all school levels reported high testing compliance and satisfaction with the implementation. Compliance was significantly associated with an increasing number of weekly tests across all school levels up to two weekly tests. Contact tracing teams were less satisfied with the cooperation with the educational authorities compared to the school employees. Higher educational level of parents was significantly associated with decreased concern of their children getting infected at school after regular testing implementation. Concerned parents were more likely to keep children at home from school, to protect all household members from becoming infected. Lack of time and communication were reported as challenging factors to implementation. Conclusion: Compliance, satisfaction, and confidence in regular testing of COVID-19 were high among stakeholders. An acceptable testing regime for a future regular testing implementation would be a home-based, bi-weekly test. Increased awareness of the importance of school attendance, safety of regular testing along with good communication and role clarification should be prioritized for stakeholders involved in regular testing.