Efficacy of novel SARS-CoV-2 rapid antigen tests in the era of omicron outbreak.

Abstract

Following the outbreak of Omicron and its subvariants, many of the currently available rapid Ag tests (RATs) showed a decrease in clinical performance. In this study, we evaluated the clinical sensitivity of the SARS-CoV-2 Rapid Antigen Test 2.0 for nasopharyngeal swabs and SARS-CoV-2 Rapid Antigen Test 2.0 Nasal for nasal swabs in 56 symptomatic individuals by comparing the results between RATs, RT-PCR, Omicron RT-PCR, and whole-genome sequencing (WGS). Furthermore, sequences of the Omicron subvariants' spike proteins were subjected to phylogenetic analysis. Both novel RATs demonstrated a high sensitivity of up to 92.86%, (95% CI 82.71%- 98.02%), 94.23%, (95% CI 83.07%- 98.49%), and 97.95% (95% CI 87.76%- 99.89%) compared to the RT-PCR, Omicron RT-PCR, and WGS, respectively. The clinical sensitivity of RATs was at its highest when the Ct value was restricted to 15≤Ct<25, with a sensitivity of 97.05% for RdRp genes. The Omicron RT-PCR analysis revealed subvariants BA.4 or BA.5 (76.8%) and BA.2.75 (16.1%). Subsequently, the WGS analysis identified BA.5 (65.5%) as the dominant subvariant. Phylogenetic analysis of the spike protein of Omicron's subvariants showed a close relationship between BA.4, BA.5, and BA.2.75. These results demonstrated that SARS-CoV-2 Rapid Antigen Test 2.0 and SARS-CoV-2 Rapid Antigen Test 2.0 Nasal are considered useful and efficient RATs for the detection of SARS-CoV-2, particularly during the current Omicron subvariants wave.