Browsing by Author "Pizarro, Gabriel"

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    Comparative evaluation of four rapid SARS-CoV-2 antigen detection tests using universal transport medium
    (2021) Weitzel, Thomas; Legarraga, Paulette; Iruretagoyena, Mirentxu; Pizarro, Gabriel; Vollrath, Valeska; Araos, Rafael; Munita, José; Porte, Lorena
    Correspondence
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    Evaluation of a novel antigen-based rapid detection test for the diagnosis of SARS-CoV-2 in respiratory samples
    (2020) Porte, Lorena; Legarraga, Paulette; Vollrath, Valeska; Aguilera, Ximena; Munita, José; Araos, Rafael; Pizarro, Gabriel; Vial, Pablo; Iruretagoyena, Mirentxu; Dittrich, Sabine; Weitzel, Thomas
    Objectives: In the context of the coronavirus disease 2019 (COVID-19) pandemic, the development and validation of rapid and easy-to-perform diagnostic methods are of high priority. This study was performed to evaluate a novel rapid antigen detection test (RDT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in respiratory samples. Methods: The fluorescence immunochromatographic SARS-CoV-2 antigen test (Bioeasy Biotechnology Co., Shenzhen, China) was evaluated using universal transport medium with nasopharyngeal (NP) and oropharyngeal (OP) swabs from suspected COVID-19 cases. Diagnostic accuracy was determined in comparison to SARS-CoV-2 real-time (RT)-PCR. Results: A total of 127 samples were included; 82 were RT-PCR-positive. The median patient age was 38 years, 53.5% were male, and 93.7% were from the first week after symptom onset. Overall sensitivity and specificity were 93.9% (95% confidence interval 86.5-97.4%) and 100% (95% confidence interval 92.1-100%), respectively, with a diagnostic accuracy of 96.1% and Kappa coefficient of 0.9. Sensitivity was significantly higher in samples with high viral loads. Conclusions: The RDT evaluated in this study showed a high sensitivity and specificity in samples mainly obtained during the first week of symptoms and with high viral loads, despite the use of a non-validated sample material. The assay has the potential to become an important tool for early diagnosis of SARS-CoV-2, particularly in situations with limited access to molecular methods.
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    Evaluation of two fluorescence immunoassays for the rapid detection of SARS-CoV-2 antigen-new tool to detect infective COVID-19 patients
    (2021) Porte, Lorena; Legarraga, Paulette; Iruretagoyena, Mirentxu; Vollrath, Valeska; Pizarro, Gabriel; Munita, José; Araos, Rafael; Weitzel, Thomas
    Background Real-Time Reverse-Transcription Polymerase Chain Reaction (RT-PCR) is currently the only recommended diagnostic method for SARS-CoV-2. However, rapid immunoassays for SARS-CoV-2 antigen could significantly reduce the COVID-19 burden currently weighing on laboratories around the world. Methods We evaluated the performance of two rapid fluorescence immunoassays (FIAs), SOFIA SARS Antigen FIA (Quidel Corporation, San Diego, CA, USA) and STANDARD F COVID-19 Ag FIA (SD Biosensor Inc., Gyeonggi-do, Republic of Korea), which use an automated reader. The study used 64 RT-PCR characterized clinical samples (32 positive; 32 negative), which consisted of nasopharyngeal swabs in universal transport medium. Results Of the 32 positive specimens, all from patients within 5 days of symptom onset, the Quidel and SD Biosensor assays detected 30 (93.8%) and 29 (90.6%) samples, respectively. Among the 27 samples with high viral loads (Ct ≤ 25), the two tests had a sensitivity of 100%. Specificity was 96.9% for both kits. Conclusion The high performance of the evaluated FIAs indicates a potential use as rapid and PCR-independent tools for COVID-19 diagnosis in early stages of infection. The excellent sensitivity to detect cases with viral loads above ~106 copies/mL (Ct values ≤ 25), the estimated threshold of contagiousness, suggests that the assays might serve to rapidly identify infective individuals.

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