Analytical Sensitivity of Lateral Flow Devices against SARS-CoV-2 Omicron Subvariants BA.4, BA.5, and BA.2.75

Rapid antigen testing has played a pivotal role in the COVID-19 pandemic, enabling quick identification of individuals with SARS-CoV-2 infection, and rapid institution of clinical and public health measures. In many settings, including Australia, rapid antigen testing is now the main modality of testing, with only one-third of SARS-CoV-2 infections now diagnosed using PCR assays (1). The ongoing emergence of new SARS-CoV-2 variants requires constant vigilance in diagnostic assay performance, including assessments of the analytical and clinical sensitivity of rapid antigen tests. Although amino acid changes in the SARS-CoV-2 spike protein are the characteristic feature of SARS-CoV-2 variants, mutations in the nucleocapsid protein (the diagnostic target of most antigen tests) can occur (1). To date, however, the performance of most antigen tests has been assessed against previously circulating variants, including the Delta and Omicron B.1.1.529 lineages (2, 3). Accordingly, we undertook a rapid assessment of the analytical sensitivity of six antigen tests, commonly used in our setting, against the Omicron sublineages BA.4, BA.5, and BA.2.75.