Retrospective clinical evaluation of 4 lateral flow assays for the detection of SARS-CoV-2 IgG

Abstract

In a Clinical Laboratory Improvement Amendments laboratory setting, we evaluated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG detection with 4 lateral flow immunoassays [LFIAs; 2 iterations from BTNX Inc. (n = 457) and 1 each from ACON Laboratories (n = 200) and SD BIOSENSOR (n = 155)]. In a cohort of primarily hospitalized, reverse-transcription polymerase chain reaction-confirmed coronavirus disease 2019 cases, sensitivity at ≥14 days from symptom onset was: BTNX kit 1, 95%; BTNX kit 2, 91%; ACON, 95%; and SD, 92%. All assays showed good concordance with the Abbott SARS-CoV-2 IgG assay at ≥14 days from symptom onset: BTNX kit 1, 99%; BTNX kit 2, 94%; ACON, 99%; and SD, 100%. Specificity, measured using specimens collected prior to SARS-CoV-2 circulation in the United States and "cross-reactivity challenge" specimens, was 98% for BTNX kit 1 and ACON and 100% for BTNX kit 2 and SD. These results suggest that LFIAs may provide adequate results for rapid detection of SARS-CoV-2.

Keywords: COVID-19; IgG; Immunoassay; Lateral flow; SARS-CoV-2; Serology.

Fig. 1

A plasma sample from an RT-PCR–confirmed COVID-19 case collected 14 days after symptom onset and tested on (left to right) Rapid Response™ COVID-19 Test Cassette (BTNX Inc.) Kit 1, Rapid Response™ COVID-19 Test Cassette (BTNX Inc.) Kit 2, SARS-COV-2 IgG/IgM Rapid Test (ACON Laboratories), and Standard Q COVID-19 IgM/IgG Duo (SD BIOSENSOR).