Since infected persons shed SARS-CoV-2 in faeces before symptoms appear, environmental surveillance (ES) may serve as an early warning system (EWS) for COVID-19 and new variants of concern. The ES of SARS-CoV-2 has been widely reviewed; however, its effectiveness as an EWS for SARS-CoV-2 in terms of timeliness, sensitivity and specificity has not been systematically assessed. We conducted a systematic review to identify and synthesise evidence on the ES of SARS-CoV-2 as an EWS to evaluate the added value for public health. Of 1,014 studies identified, we considered 29 for a qualitative synthesis of the timeliness of ES as an EWS for COVID-19, while six studies were assessed for the ability to detect new variants and two for both aims. The synthesis indicates ES may serve as an EWS of 1–2 weeks. ES could complement clinical surveillance for SARS-CoV-2; however, its cost–benefit value for public health decisions needs to be assessed based on the stage of the pandemic and resources available. Studies focusing methodological knowledge gaps as well as how to use and interpret ES signals for public health actions are needed, as is the sharing of knowledge within countries/areas with long experience of such surveillance.

由于感染者在症状出现之前就在粪便中排出了 SARS-CoV-2，因此环境监测 (ES) 可以作为 COVID-19 和关注的新变体的早期预警系统 (EWS)。SARS-CoV-2 的 ES 已被广泛审查；然而，它作为 SARS-CoV-2 的 EWS 在及时性、敏感性和特异性方面的有效性尚未得到系统评估。我们进行了系统评价，以识别和综合关于 SARS-CoV-2 的 ES 作为 EWS 的证据，以评估对公共卫生的附加值。在确定的 1,014 项研究中，我们考虑了 29 项对 ES 作为 COVID-19 的 EWS 的及时性的定性综合，而对 6 项研究评估了检测新变体的能力，2 项针对两个目标进行了评估。综合表明 ES 可以作为 1-2 周的 EWS。ES 可以补充 SARS-CoV-2 的临床监测；但是，需要根据大流行的阶段和可用资源来评估其对公共卫生决策的成本效益价值。需要针对方法学知识差距以及如何使用和解释 ES 信号进行公共卫生行动的研究，以及在具有长期此类监测经验的国家/地区内共享知识。