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.
ABSTRACT
Immunity with SARS-CoV-2 infection during the acute phase is not sufficiently well understood to differentiate mild from severe cases and identify prognostic markers. We evaluated the immune response profile using a total of 71 biomarkers in sera from patients with SARS-CoV-2 infection, confirmed by RT-PCR and controls. We correlated biological marker levels with negative control (C) asymptomatic (A), nonhospitalized (mild cases-M), and hospitalized (severe cases-S) groups. Among angiogenesis markers, we identified biomarkers that were more frequently elevated in severe cases when compared to the other groups (C, A, and M). Among cardiovascular diseases, there were biomarkers with differences between the groups, with D-dimer, GDF-15, and sICAM-1 higher in the S group. The levels of the biomarkers Myoglobin and P-Selectin were lower among patients in group M compared to those in groups S and A. Important differences in cytokines and chemokines according to the clinical course were identified. Severe cases presented altered levels when compared to group C. This study helps to characterize biological markers related to angiogenesis, growth factors, heart disease, and cytokine/chemokine production in individuals infected with SARS-CoV-2, offering prognostic signatures and a basis for understanding the biological factors in disease severity.