Carcereny, AlbertLópez Romalde, JesúsLois, MartaPolo Montero, DavidGuix, Susana2025-01-182025-01-182021-08-16Environ. Sci. Technol. 2021, 55, 17, 11756–117661520-5851https://hdl.handle.net/10347/38708Since its first identification in the United Kingdom in late 2020, the highly transmissible B.1.1.7 variant of SARS-CoV- 2 has become dominant in several countries raising great concern. We developed a duplex real-time RT-qPCR assay to detect, discriminate, and quantitate SARS-CoV-2 variants containing one of its mutation signatures, the ΔHV69/70 deletion, and used it to trace the community circulation of the B.1.1.7 variant in Spain through the Spanish National SARS-CoV-2 Wastewater Surveillance System (VATar COVID-19). The B.1.1.7 variant was detected earlier than clinical epidemiological reporting by the local authorities, first in the southern city of Máĺaga (Andalucía) in week 20_52 (year_week), and multiple introductions during Christmas holidays were inferred in different parts of the country. Wastewater-based B.1.1.7 tracking showed a good correlation with clinical data and provided information at the local level. Data from wastewater treatment plants, which reached B.1.1.7 prevalences higher than 90% for ≥2 consecutive weeks showed that 8.1 ± 2.0 weeks were required for B.1.1.7 to become dominant. The study highlights the applicability of RT-qPCR-based strategies to track specific mutations of variants of concern as soon as they are identified by clinical sequencing and their integration into existing wastewater surveillance programs, as a cost-effective approach to complement clinical testing during the COVID-19 pandemic.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/SARS-CoV-2COVID-19B.1.1.7 variantWastewater-based epidemiology (WBE)RT-qPCRNGS2420 Virologíajournal article10.1021/acs.est.1c03589open access