Wastewater based epidemiology (WBE) emerged as a key monitoring tool during the COVID-19 pandemic. BioSS developed an analysis pipeline that allows us to report the latest findings to the Scottish Government and other stakeholders.

Scotland introduced a Wastewater-based monitoring system in summer 2020 with samples taken at Wastewater Treatment Works (WWTW) by Scottish Water (SW). These were then analysed by the Scottish Environmental Protection Agency (SEPA) using qPCR to quantify levels of COVID-19 RNA.

By early 2021, more than 100 WWTWs were regularly sampled, covering 80% of the Scottish population. Since December 2020, Biomathematics & Statistics Scotland (BioSS) has been funded by the Scottish Government to statistically analyse and visualise the data, in terms of what wastewater has to say about COVID-19 prevalence. This is a complex task as the measured levels do not only depend on the number of COVID-19 cases at the time but are influenced by a series of other factors like the amount of water going through a WWTW on the sampling day, the population covered by the catchment area and also lab-specific factors, and demonstrate a significant degree of variability.

The role of BioSS

BioSS has developed an analysis pipeline for this purpose that allows us to report the latest findings to the Scottish Government and other stakeholders on a weekly basis. Parts of these reports are made available to the general public every other week as part of the Scottish Government’s research findings, that can be found at the Scottish Government website. Our reports also feed into regular reports issued by Public Health Scotland and are used to estimate the current reproductive number R by Scottish Government modellers. With no population wide testing anymore and the Office of National Statistics Coronavirus Infection Survey being published with some delay, the COVID-19 levels in wastewater currently are the most up-to-date data resource to assess the state of the pandemic across Scotland.