SARS-CoV-2 RNA quantification in wastewater has emerged as a relevant additional means to monitor the COVID-19 pandemic. However, the concentration can be affected by black water dilution factors or movements of the sewer shed population, leading to misinterpretation of measurement results. The aim of this study was to evaluate the performance of different indicators to accurately interpret SARS-CoV-2 in wastewater. Weekly/bi-weekly measurements from three cities in France were analysed from February to September 2021. The concentrations of SARS-CoV-2 gene copies were normalised to the faecal-contributing population using simple sewage component indicators. To reduce the measurement error, a composite index was created to combine simultaneously the information carried by the simple indicators. The results showed that the regularity (mean absolute difference between observation and the smoothed curve) of the simple indicators substantially varied across sampling points. The composite index consistently showed better regularity compared to the other indicators and was associated to the lowest variation in correlation coefficient across sampling points. These findings suggest the recommendation for the use of a composite index in wastewater-based epidemiology to compensate for variability in measurement results.

废水中的 SARS-CoV-2 RNA 定量已成为监测 COVID-19 大流行的相关附加手段。但是，浓度会受到黑水稀释因素或下水道棚人口流动的影响，导致对测量结果的误解。本研究的目的是评估不同指标的性能，以准确解释废水中的 SARS-CoV-2。分析了 2021 年 2 月至 2021 年 9 月法国三个城市的每周/双周测量值。使用简单的污水成分指标将 SARS-CoV-2 基因拷贝的浓度标准化为粪便贡献人群。为了减少测量误差，我们创建了一个综合指数来同时结合简单指标所携带的信息。结果表明，简单指标的规律性（观测值与平滑曲线之间的平均绝对差）在不同采样点之间存在显着差异。与其他指标相比，综合指数始终表现出更好的规律性，并且与采样点之间相关系数的最低变化相关。这些发现建议在基于废水的流行病学中使用综合指数来补偿测量结果的可变性。