tetano
Editor, Senior Moderator
J Clin Microbiol
. 2021 Jan 22;JCM.03149-20.
doi: 10.1128/JCM.03149-20. Online ahead of print.
Quantitative measurement of anti-SARS-CoV-2 antibodies: Analytical and clinical evaluation
Victoria Higgins[SUP] 1 [/SUP], Anselmo Fabros[SUP] 2 [/SUP], Vathany Kulasingam[SUP] 3 2 [/SUP]
Affiliations
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of Coronavirus Disease 2019 (COVID-19). While molecular-based testing is used to diagnose COVID-19, serologic testing of antibodies specific to SARS-CoV-2 is used to detect past infection. While most serologic assays are qualitative, a quantitative serologic assay was recently developed that measures antibodies against the S protein, the target of vaccines. Quantitative antibody determination may help determine antibody titer, facilitate longitudinal monitoring of the antibody response, including antibody response to vaccines. We evaluated the quantitative Roche Elecsys? Anti-SARS-CoV-2 S assay. Specimens from 167 PCR-positive patients and 103 control specimens were analyzed using the Elecsys? Anti-SARS-CoV-2 S assay on the cobas e411 (Roche Diagnostics). Analytical evaluation included assessing linearity, imprecision, and analytical sensitivity. Clinical evaluation included assessing clinical sensitivity, specificity, cross-reactivity, positive predictive value (PPV), negative predictive value (NPV), and serial sampling from the same patient. The Elecsys? Anti-SARS-CoV-2 S assay exhibited highest sensitivity of 84.0% 15-30 days post-PCR positivity, no cross-reactivity, specificity and PPV of 100%, and NPV between 98.3%-99.8% ≥14 days post-PCR positivity, depending on the seroprevalence estimate. Imprecision was <2% at 9.06 U/mL across 6 days, the negative QC was consistently negative (<0.40 U/mL), the manufacturer's claimed limit of quantitation of 0.40 U/mL was verified, and linearity across the analytical measuring range was observed, except at the low end (<20 U/mL). Lastly antibody response showed high inter-individual variation in level and time of peak antibody titre and trends over time.
. 2021 Jan 22;JCM.03149-20.
doi: 10.1128/JCM.03149-20. Online ahead of print.
Quantitative measurement of anti-SARS-CoV-2 antibodies: Analytical and clinical evaluation
Victoria Higgins[SUP] 1 [/SUP], Anselmo Fabros[SUP] 2 [/SUP], Vathany Kulasingam[SUP] 3 2 [/SUP]
Affiliations
- PMID: 33483360
- DOI: 10.1128/JCM.03149-20
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of Coronavirus Disease 2019 (COVID-19). While molecular-based testing is used to diagnose COVID-19, serologic testing of antibodies specific to SARS-CoV-2 is used to detect past infection. While most serologic assays are qualitative, a quantitative serologic assay was recently developed that measures antibodies against the S protein, the target of vaccines. Quantitative antibody determination may help determine antibody titer, facilitate longitudinal monitoring of the antibody response, including antibody response to vaccines. We evaluated the quantitative Roche Elecsys? Anti-SARS-CoV-2 S assay. Specimens from 167 PCR-positive patients and 103 control specimens were analyzed using the Elecsys? Anti-SARS-CoV-2 S assay on the cobas e411 (Roche Diagnostics). Analytical evaluation included assessing linearity, imprecision, and analytical sensitivity. Clinical evaluation included assessing clinical sensitivity, specificity, cross-reactivity, positive predictive value (PPV), negative predictive value (NPV), and serial sampling from the same patient. The Elecsys? Anti-SARS-CoV-2 S assay exhibited highest sensitivity of 84.0% 15-30 days post-PCR positivity, no cross-reactivity, specificity and PPV of 100%, and NPV between 98.3%-99.8% ≥14 days post-PCR positivity, depending on the seroprevalence estimate. Imprecision was <2% at 9.06 U/mL across 6 days, the negative QC was consistently negative (<0.40 U/mL), the manufacturer's claimed limit of quantitation of 0.40 U/mL was verified, and linearity across the analytical measuring range was observed, except at the low end (<20 U/mL). Lastly antibody response showed high inter-individual variation in level and time of peak antibody titre and trends over time.