Examining the impact of different scales on COVID-19 monitoring in sewerage catchment areas: Insights from Latvia

• Explores COVID-19 monitoring trends across multiple wastewater levels, including the use of metagenomics. • Identifies consistent COVID-19 patterns across catchment levels, mapping virus spread. • Highlights gut microbiome monitoring as a potential early COVID-19 warning tool. The spread and transmission of coronavirus, SARS-CoV-2, have become a significant global concern. As the SARS-CoV-2 virus can be released into the environment through various human excretions, it provides a possibility for early detection and identification within a population through the use of wastewater-based epidemiology (WBE). With the rapid progress in the application of WBE during the COVID-19 pandemic, researchers have been able to provide evidence of SARS-CoV-2 shedding in wastewater and aid in decision-making for public health measures. However, there is a lack of research on potential trends and correlations between different levels of wastewater sample analysis, from building-level to municipality-level. Therefore, this study aims to fill this gap and also explore the use of metagenomic analysis in addition to the amount of viral RNA concentration in wastewater samples for COVID-19 monitoring at different levels. Results from monitoring indicated consistent patterns of COVID-19 and variants at the building, community, and municipality levels. However, there was a statistical difference in transmission dynamics at the building level during the spring season, possibly due to localized factors. Thus, the comparison of monitoring data from COVID-19 across different sewage catchment areas plays a crucial role in understanding the geographical spread of COVID-19. Metagenome analysis revealed a predominance of gut-associated microbes in wastewater, but no significant seasonal variations were observed. Further research is necessary to fully understand the relationship between changes in the gut microbiome and the distribution of COVID-19.