ABSTRACT
OBJECTIVES: We aimed to investigate the real-life performance of the rapid antigen test (RAT) in the context of a primary healthcare setting, including symptomatic and asymptomatic individuals that sought diagnostic during a Omicron infection wave. METHODS: We prospectively accessed the performance of the DPP® SARS-CoV-2 Antigen test in the context of an omicron-dominant real-life setting. We evaluated 347 unselected individuals (all-comers) from a public testing center in Brazil, performing the RAT diagnosis at point-of-care with fresh samples. The combinatory result from two distinct RT-qPCR methods was employed as reference and 13 samples with discordant PCR results were excluded. RESULTS: The assessment of the rapid test in 67 PCR-positive and 265 negative samples revealed an overall sensitivity of 80.5% (CI95% = 69.1 - 89.2%), specificity of 99.2% (CI95% = 97.3 - 99.1%) and positive/negative predictive values higher than 95%. However, we observed that the sensitivity was dependent on the viral load (sensitivity in Ct<31 = 93.7%, CI = 82.8 - 98.7%; Ct>31 = 47.4%, CI = 24.4 - 71.1%). The positive samples evaluated in the study were Omicron (BA.1/BA.1.1) by whole-genome sequencing (n=40) and multiplex RT-qPCR (n=17). CONCLUSIONS: Altogether, the data obtained from a real-life prospective cohort supports that the RAT sensitivity for Omicron remains high and underscores the reliability of the test for COVID-19 diagnosis in settings with high disease prevalence and limited PCR testing capability.