Regional Replacement of SARS-CoV-2 Variant Omicron BA.1 with BA.2 as Observed through Wastewater Surveillance

Greater knowledge 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 solid samples from eight publicly owned treatment works in the greater Bay Area of California, United States, 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 sublineage circulation. The results suggest that concerted efforts to design RT-PCR assays that target variant and variant sublineage characteristic mutations for wide-scale wastewater monitoring implementation will be informative for pandemic response.