COVID-19 wastewater based epidemiology: long-term monitoring of 10 WWTP in France reveals the importance of the sampling context

SARS-CoV-2 wastewater-based epidemiology (WBE) has been advancedas a relevant indicator of distribution of COVID-19 in communities, supporting classical testing and tracing epidemiological approaches. An extensive sampling campaign, including ten municipal wastewater treatment plants, has been conducted in different cities of France over a 20-weeks period, encompassing the second peak of COVID-19 outbreak in France. A well-recognised ultrafiltration - RNA extraction - RT-qPCR protocol was used and qualified, showing 5.5 +/-0.5% recovery yield on heat-inactivated SARS-CoV-2. Importantly the whole, solid and liquid, fraction of wastewater was used for virus concentration in this study. Campaign results showed medium- to strong-correlation between SARS-CoV-2 WBE data and COVID-19 prevalence. To go further, WWTP inlet flow rate and raining statistical relationships were studied and taken into account for each WWTP in order to calculate contextualized SARS-CoV-2 loads. This metric presented improved correlation strengths with COVID-19 prevalence for WWTP particularly submitted and sensitive to rain. Such findings highlighted that SARS-CoV-2 WBE data ultimately require to be contextualised for relevant interpretation. HighlightsO_LIFirst study monitoring inlet of 10 WWTPs located in France for SARS-CoV-2 RNA quantification over a 20-weeks period encompassing the second peak of COVID-19 outbreak C_LIO_LIViral recovery yield was 5.5 % +/-0.5% using heat-inactivated SARS-CoV-2 C_LIO_LIMedium to high Spearmans correlation strength was observed between SARS-CoV-2 WBE and COVID-19 prevalence data C_LIO_LIConsidering sampling context (ei. rain events) improved data consistency and correlation strength C_LI Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=98 SRC="FIGDIR/small/21256751v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1127b40org.highwire.dtl.DTLVardef@59aa60org.highwire.dtl.DTLVardef@c0accforg.highwire.dtl.DTLVardef@1917ba9_HPS_FORMAT_FIGEXP M_FIG C_FIG