Regional replacement of SARS-CoV-2 variant BA.1 with BA.2 as observed through wastewater surveillance

An understanding of circulating SARS-CoV-2 variants can inform pandemic response, vaccine development, disease epidemiology, and use of monoclonal antibody treatments. We developed custom assays targeting characteristic mutations in SARS-CoV-2 variants Omicron BA.1 and BA.2 and confirmed their sensitivity and specificity in silico and in vitro . We then applied these assays to daily wastewater solids samples from eight publicly owned treatment works in the greater Bay Area of California, USA, over four months to obtain a spatially and temporally intensive data set. We documented regional replacement of BA.1 with BA.2 in agreement with, and ahead of, clinical sequencing data. This study highlights the utility of wastewater surveillance for real time tracking of SARS-CoV-2 variant circulation.