Comparison of six antibody assays and two combination assays for COVID-19

Abstract

Introduction In this work, six SARS-CoV-2-specific antibody assays were evaluated, namely, two pan-immunoglobulin (pan-Ig) assays [Roche Elecsys Anti-SARS-CoV-2 (named "Elecsys" in this study) and the PerkinElmer SuperFlex™ Anti-SARS-CoV-2 Ab Assay (SuperFlex_Ab)], two IgM assays [SuperFlex™ Anti-SARS-CoV-2 IgM Assay (SuperFlex_IgM) and YHLO iFlash-SARS-CoV-2 IgM (iFlash_IgM)], and two IgG assays [SuperFlex™ Anti-SARS-CoV-2 IgG Assay (SuperFlex_IgG) and iFlash-SARS-CoV-2 IgG (iFlash_IgG)]. Combination assays of SuperFlex™ (SuperFlex_any) and iFlash (iFlash_any) were also evaluated. Methods A total of 438 residual serum samples from 54 COVID-19 patients in the COVID-19 group and 100 samples from individuals without evidence of SARS-CoV-2 infection in the negative control group were evaluated. Results In the early stage of COVID-19 infection, within 14 days of symptom onset, the seropositive rate was lower than that of the late stage 15 days after onset (65.4% vs 99.6%). In the total period, the pan-Ig and IgG assays had higher sensitivity (90.8–95.3%) than the IgM assays (36.5–40.7%). SuperFlex_Ab and SuperFlex_any had higher sensitivity than Elecsys and SuperFlex_IgG (p < 0.05). The specificity of all the assays was 100%, except for SuperFlex_IgM (99.0%). The concordance rate between each assay was higher (96.4–100%) in the late stage than in the early stage (77.4–98.1%). Conclusion For the purpose of COVID-19 diagnosis, antibody testing should be performed 15 days after onset. For the purpose of epidemiological surveillance, highly sensitive assays should be used as much as possible, such as SuperFlex_Ab, iFlash_IgG and their combination. IgM assays were not suitable for these purposes.

Comparison of one single-antigen assay and three multi-antigen SARS-CoV-2 IgG assays in Nigeria

“…Though the sample sizes were small for DBS, our results indicated that DBS could serve as an alternate, especially for individuals infected for at least 15 days and above. A similar study suggested that the positivity rate of SARS-CoV-2 antibody testing was relatively low within 14 days of symptom onset than 15 days after symptom inception [40] . Therefore, an antibody-based test for epidemiological surveillance after 15 days is recommended.…”

Anti-Spike Protein to Determine SARS-CoV-2 Antibody Levels: Is There a Specific Threshold Conferring Protection in Immunocompromised Patients?

“…As previously observed by Perkmann et al although all assays showed good agreement with the Genscript sVNT, they were not interchangeable, even when converted to BAU/ml using the WHO international standard for SARS-CoV-2 immunoglobulin levels [10]. The differences in the commercial assays used in this study are related to the components of the tests (the spike antigen epitopes used, the different isolates of the SARS-CoV-2, and the quantification of either total antibodies or only IgG) [18][19][20]. This implies that the cutoff values provided for the respective test systems are valid only for the diagnosis of a past infection and do not necessarily represent a threshold value for the presence of sufficient neutralizing activity.…”

Comparison of diagnostic performances of different serological tests for SARS‐CoV‐2 antibody detection in cats and dogs

“…Reliable methods for antibody detection are essential to understand susceptibility and immune‐response to SARS‐CoV‐2 in animals and assays with high sensitivity should be used for epidemiological surveillance (Yamamoto et al., 2022). However, the gold standard VNT execution requires BSL‐3 laboratories and trained personnel, making it inaccessible for a wider community of diagnostic and research laboratories.…”

“…In humans, virus neutralization test (VNT) is considered the gold standard for the detection of serum neutralizing antibodies that are primarily against the S1, S2 and RBD domains of the SARS‐CoV‐2 spike protein (Brouwer et al., 2020), represent only a small subset of the total polyclonal immune response (Girl et al., 2022) and are fundamental for the evaluation of convalescent plasma and efficacy of vaccination (Yamamoto et al., 2022). VNT is considered the gold standard also for SARS‐CoV‐2 antibody detection in pets (Embregts et al., 2021; Perera et al., 2021).…”