Analytical performance of lateral flow immunoassay for SARS-CoV-2 exposure screening on venous and capillary blood samples

Abstract

Objectives We validate the use of a lateral flow immunoassay (LFI) intended for rapid screening and qualitative detection of anti-SARS-CoV-2 IgM and IgG in serum, plasma, and whole blood, and compare results with ELISA. We also seek to establish the value of LFI testing on blood obtained from a capillary blood sample. Methods Samples collected by venous blood draw and finger stick were obtained from patients with SARS-CoV-2 detected by RT-qPCR and control patients. Samples were tested with Biolidics 2019-nCoV IgG/IgM Detection Kit lateral flow immunoassay, and antibody calls were compared with ELISA. Results Biolidics LFI showed clinical sensitivity of 92% with venous blood at 7 days after PCR diagnosis of SARS-CoV-2. Test specificity was 92% for IgM and 100% for IgG. There was no significant difference in detecting IgM and IgG with Biolidics LFI and ELISA at D0 and D7 ( p = 1.00), except for detection of IgM at D7 ( p = 0.04). Capillary blood of SARS-CoV-2 patients showed 93% sensitivity for antibody detection. Conclusions Clinical performance of Biolidics 2019-nCoV IgG/IgM Detection Kit is comparable to ELISA and was consistent across sample types. This provides an opportunity for decentralized rapid testing and may allow point-of-care and longitudinal self-testing for the presence of anti-SARS-CoV-2 antibodies.

COVID-19 Antibody Detecting Rapid Diagnostic Tests Show High Cross-Reactivity When Challenged with Pre-Pandemic Malaria, Schistosomiasis and Dengue Samples

“…However, five RDT products explicitly prescribed to consider any shade of color as a positive reading. In addition, low intensity has been reported frequently among true-positive test lines in COVID-19 RDTs assessed in independent evaluation studies or deployed in seroprevalence studies in Europe [ 14 , 54 , 55 , 56 , 57 , 58 , 59 ]; in the latter studies, proportions of low intensity were comparable to the present cross-reactive line intensities [ 58 , 59 ]. In the case of seroprevalence studies, this may partly be explained by lower antibody levels in non-symptomatic individuals [ 60 ].…”

Diagnostic Properties of Three SARS-CoV-2 Antibody Tests

“…Numerous rapid tests options have appeared on the market, however, due to the highly variable sensitivity and specificity of these assays for COVID-19 immunity, internal validation became necessary. Serologic assessment provides valuable information on past exposure using venous and capillary blood samples, although the protective effect of anti-SARS-CoV-2 antibodies remains uncertain [16].…”

Prevalencia de anticuerpos contra el SARS-CoV-2 según el estatus socioeconómico y étnico en una encuesta nacional de Brasil

“…Estos estudios estimaron que la sensibilidad y especificidad de la prueba es de 84,8% y 99,0%, respectivamente. Se ha indicado que el uso de sangre capilar para estimar la seroprevalencia tiende a aumentar la tasa de resultados negativos falsos ( 18 ), pero esto no se ha reproducido en otros estudios ( 19 ). Cabe señalar que en nuestro estudio de validación ( 8 ) se utilizó sangre capilar y la sensibilidad observada fue similar a la notificada en otros estudios.…”