Performance of a qualitative rapid chromatographic immunoassay to diagnose COVID-19 in patients in a middle-income country

• Published in: Journal of clinical virology Vol. 131; p. 104592
• Main Authors: Costa, Silvia Figueiredo, Buss, Lewis, Espinoza, Evelyn Patrícia Sanchez, Vieira, Jose Mauro, de Oliveira da Silva, Lea Campos, de Souza, Regina Maia, Neto, Lauro Perdigão, Porto, Ana Paula Matos, Lazari, Carolina, dos Santos, Vera Aparecida, da Silva Duarte, Alberto, Nastri, Ana Catharina, da Costa Leite, Gabriel Fialkovitz, Manuli, Erika, de Oliveira, Maura Salaroli, Zampelli, Daniella Bosco, Pastore, Laerte, Segurado, Aluísio Cotrim, Levin, Anna S., Sabino, Ester
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2020
• Subjects: Adult; Aged; Aged, 80 and over; Antibodies, Viral - blood; Betacoronavirus; Brazil; Chromatography; Clinical Laboratory Techniques; Coronavirus Infections - diagnosis; Coronavirus Infections - immunology; COVID-19; COVID-19 Testing; ELISA; Female; Hospitalization - statistics & numerical data; Humans; Immunoassay; Immunoglobulin G - blood; Male; Middle Aged; Pandemics; Pneumonia, Viral - diagnosis; Pneumonia, Viral - immunology; Prospective Studies; qualitative rapid chromatographic immunoassays; SARS-CoV-2; Sensitivity and Specificity; Short Communication; Young Adult; Brazil; SARS-cov-2; qualitative rapid chromatographic immunoassays; ELISA
• ISSN: 1386-6532; 1873-5967
• DOI: 10.1016/j.jcv.2020.104592

•COVID-19 diagnosis; high sensitivity and specificity qualitative rapid chromatographic immunoassays; can be used for the diagnosis of RT-PCR-negative patients. We evaluated a rapid chromatographic immunoassay (IgG/IgM antibodies) and an ELISA assay to diagnose COVID-19 in patient sat two Brazilian hospitals. A total of 122 subjects with COVID-19 were included: 106 SARS-COV-2 RT-PCR-positive patients and 16 RT-PCR-negative patients with symptoms and chest computed tomography (CT) consistent with COVID-19. Ninety-six historical blood donation samples were used as controls. Demographic and clinical characteristics were retrieved from electronic records. Sensitivity and specificity were calculated, as were their 95% binomial confidence intervals using the Clopper-Pearson method. All analyses were performed in R version 3.6.3. The sensitivity of the chromatographic immunoassay in all RT-PCR-positive patients, irrespective of the timing of symptom onset, was 85.8% (95% binomial CI 77.7% to 91.9%). This increased with time after symptom onset, and at >14 days was 94.9% (85.9% to 98.9%). The specificity was 100% (96.4% to 100%). 15/16 (94%) RT- PCR-negative cases tested positive. The most frequent comorbidities were hypertension and diabetes mellitus and the most frequent symptoms were fever, cough, and dyspnea. All RT-PCR-negative patients had pneumonia. The most frequent thoracic CT findings were ground glass changes (n = 11, 68%), which were bilateral in 9 (56%) patients, and diffuse reticulonodular infiltrates (n = 5, 31%). The COVID-19 rapid chromatographic immunoassay evaluated in this study had a high sensitivity and specificity using plasma, particularly after 14 days from symptom onset. ELISA and qualitative rapid chromatographic immunoassays can be used for the diagnosis of RT-PCR-negative patients.