Performance evaluation of two SARS-CoV-2 IgG/IgM rapid tests (Covid-Presto and NG-Test) and one IgG automated immunoassay (Abbott)

Abstract

The aim of this study was to assess the analytical performances, sensitivity and specificity, of two rapid tests (Covid- Presto® test rapid Covid-19 IgG/IgM and NG-Test® IgM-IgG COVID-19) and one automated immunoassay (Abbott SARS-CoV-2 IgG) for detecting anti- SARS-CoV-2 antibodies. This study was performed with: (i) a positive panel constituted of 88 SARS-CoV-2 specimens collected from patients with a positive SARS-CoV-2 RT-PCR, and (ii) a negative panel of 120 serum samples, all collected before November 2019, including 64 samples with a cross-reactivity panel. Sensitivity of Covid-Presto® test for IgM and IgG was 78.4% and 92.0%, respectively. Sensitivity of NG-Test® for IgM and IgG was 96.6% and 94.9%, respectively. Sensitivity of Abbott IgG assay was 96.5% showing an excellent agreement with the two rapid tests (κ = 0.947 and κ = 0.936 for NGTest ® and Covid-Presto® test, respectively). An excellent agreement was also observed between the two rapid tests (κ = 0.937). Specificity for IgM was 100% and 86.5% for Covid-Presto® test and NG-Test®, respectively. Specificity for IgG was 92.0%, 94.9% and 96.5% for Covid-Presto®, NGTest ®, and Abbott, respectively. Most of the false positive results observed with NG-Test® resulted from samples containing malarial antibodies. In conclusion, performances of these 2 rapid tests are very good and comparable to those obtained with automated immunoassay, except for IgM specificity with the NG-Test®. Thus, isolated IgM should be cautiously interpreted due to the possible false-positive reactions with this test. Finally, before their large use, the rapid tests must be reliably evaluated with adequate and large panel including early seroconversion and possible cross-reactive samples.

Diagnostic and analytical performance evaluation of ten commercial assays for detecting SARS-CoV-2 humoral immune response

“…However, the Ag-source clearly appeared not to be the only factor attributing to diagnostic sensitivity ( Table 1 ). Our data are in concordance with other head to head SARS-CoV-2 antibody comparison studies ( Lassaunière et al, 2020 ; Van Elslande et al, 2020 ; National SARS-CoV-2 Serology Assay Evaluation Group, 2020 ; Pieri et al, 2020 ; Charpentier et al, 2020 ; Herroelen et al, 2020 ; Perkmann et al, 2020 ) and, if compared on the same level of specificity (95%), the R-N revealed the best overall sensitivity (84.0% [74.1–91.2]) versus DS-S the lowest (61.7% [50.3–72.3]). For symptomatic patients, all tests, except for TD-S, revealed a sensitivity of 100% ≥ 20 days after symptom onset ( Table 1 ).…”

A lateral flow immunoassay test performance in SARS-CoV-2 seroprevalence surveys: a validation study among healthcare workers

“…The sensitivity and specificity reported in our study for the NG-Test ® are lower than those reported in three recent publications [ 1 , 5 , 6 ], all conducted retrospectively on sera. One explanation for the lower sensitivity and specificity observed in our study relative to these three studies may be the different characteristics of the included participants: the vast majority of participants in our study were women <50 years of age, whereas the cases were mainly men over 50 in the other three studies (median age = 58 years for Dortet et al) [ 1 , 5 , 6 ]. In addition, the clinical presentation of COVID-19 was also different in our population: no HCWs required admission for COVID-19, whereas most participants in the three published studies were hospitalised (up to 82% in the study of Dortet et al) [ 1 , 5 , 6 ].…”

“…This suggests that the NG-Test ® results for IgM must be interpreted with caution. This result is in accordance with that of the study of Charpentier et al [ 6 ], which reported lower specificity than the two other studies on sera.…”

“…One explanation for the lower sensitivity and specificity observed in our study relative to these three studies may be the different characteristics of the included participants: the vast majority of participants in our study were women <50 years of age, whereas the cases were mainly men over 50 in the other three studies (median age = 58 years for Dortet et al) [ 1 , 5 , 6 ]. In addition, the clinical presentation of COVID-19 was also different in our population: no HCWs required admission for COVID-19, whereas most participants in the three published studies were hospitalised (up to 82% in the study of Dortet et al) [ 1 , 5 , 6 ]. Several publications have suggested that the immune response may be stronger in older male patients with severe forms of COVID-19 [ 7–9 ].…”

Evaluation of SARS-CoV-2 total antibody detection via a lateral flow nanoparticle fluorescence immunoassay

“…These rapid assays provide a low-throughput antibody testing option for laboratories with limited resources and are particularly useful for epidemiologic field studies. However, a meta-analysis evaluating the diagnostic accuracy of SARS-CoV-2 serologic testing concluded that LFIAs were consistently less sensitive than ELISA or CLIA methods [ 9 ], and subsequent studies have reported a wide range of sensitivities and specificities [ [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] ]. Nevertheless, the Infectious Diseases Society of America (IDSA) recommends against the use of IgG or IgM antibody combination tests, where detecting either antibody isotype is used to define a positive result [ 7 ].…”