Numerous SARS-CoV-2 variants are emerging as the epidemic continues, inducing new waves of contamination. In July 2023, a new variant named BA.2.86 was identified, raising concerns about its potential for viral escape, even in an immune population. The reduction in patient-centered testing and the identification of variants by sequencing means that we are now blind to the spread of this new variant. The aim of this study was to track the signature of this variant in wastewater in Paris, France. This variant showed a very rapid spread, highly correlated with national flash studies involving sequencing of clinical samples, but with a moderate impact on virus circulation. This easy-to-implement approach enabled us to monitor the emergence and spread of this new variant in real time at low cost.