Evaluation of wastewater surveillance results for SARS-CoV-2 at the national scale in the Slovak Republic

As the COVID-19 transits to endemicity, the frequency of clinical testing and its utility for determining lineage prevalence has declined. This situation is not unique to Slovakia but reflects a global trend, as attention shifts from COVID-19 to other post-pandemic issues and emerging global health challenges. Nevertheless, the pandemic itself has spurred advancements in monitoring the epidemiological situation. At the beginning of the pandemic, genomic surveillance was carried out through sequencing of individual COVID-19 cases. Subsequently, many countries implemented wastewater surveillance to monitor the prevalence of SARS-CoV-2 variants in the community. In the present study, we collected and analysed 1715 virus-positive samples from 64 wastewater treatment plants across Slovakia, serving 69 % of the population connected to the wastewater treatment pipelines. Here, we show that wastewater sequencing is effective in detecting the emergence of new virus lineages. Additionally, we can assume that wastewater surveillance provides results that are approximately consistent when compared with clinical testing at both national and city levels, concurrently providing information on variant lineages which have not been detected in clinical cases due to reduced clinical testing. Our study demonstrates and concludes the value of wastewater-based surveillance strategies in the Slovakia, establishing it as an important and supportive tool for monitoring public health and serving as an early warning system in times when clinical testing is either declining or unavailable.