SARS-CoV-2 Serology Status Detected by Commercialized Platforms Distinguishes Previous Infection and Vaccination Adaptive Immune Responses
Authors: Suhandynata Raymond T. , Bevins Nicholas J. , Tran Jenny T. , Huang Deli , Hoffman Melissa A. , Lund Kyle , Kelner Michael J. , McLawhon Ronald W. , Gonias Steven L. , Nemazee David , Fitzgerald Robert L. 
Published: March 2021

Background

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has infected over 110 million individuals and led to 2.5 million deaths worldwide. As more individuals are vaccinated, the clinical performance and utility of SARS-CoV-2 serology platforms needs to be evaluated.

Methods

The ability of four commercial SARS-CoV-2 serology platforms to detect previous infection or vaccination were evaluated using a cohort of 53 SARS-CoV-2 PCR-positive patients, 89 SARS-CoV-2-vaccinated healthcare workers (Pfizer or Moderna), and 127 SARS-CoV-2 negative patients. Serology results were compared to a cell based SARS-CoV-2 pseudovirus (PSV) neutralizing antibodies assay.

Results

The Roche S-(spike) antibody and Diazyme neutralizing antibodies (NAbs) assays detected adaptive immune response in 100.0% and 90.1% of vaccinated individuals who received two-doses of vaccine (initial and booster), respectively. The Roche N-(nucleocapsid) antibody assay and Diazyme IgG assay did not detect adaptive immune response in vaccinated individuals. The Diazyme Nabs assay correlated with the PSV SARS-CoV-2 ID50 neutralization titers (R2= 0.70), while correlation of the Roche S-antibody assay was weaker (R2= 0.39). Median PSV SARS-CoV-2 ID50 titers more than doubled in vaccinated individuals who received two-doses of the Moderna vaccine (ID50: 597) compared to individuals that received a single dose (ID50: 284).

Conclusions

The Roche S-antibody and Diazyme NAbs assays robustly detected adaptive immune responses in SARS-CoV-2 vaccinated individuals and SARS-CoV-2 infected individuals. The Diazyme NAbs assay strongly correlates with the PSV SARS-CoV-2 NAbs in vaccinated individuals. Understanding the reactivity of commercially available serology platforms is important when distinguishing vaccination response versus natural infection.

The Roche S (spike protein)-antibody and Diazyme neutralizing-antibodies (NAbs) assays were evaluated for their clinical utility in the detection of SARS-CoV-2 related adaptive immune responses by testing SARS-CoV-2 PCR-confirmed patients, SARS-CoV-2-vaccinated individuals, and SARS-CoV-2-negative individuals. Commercial serology results were compared to results generated using a cell-based SARS-CoV-2 pseudovirus (PSV) NAbs assay and previously validated SARS-CoV-2 commercial serology assays (Roche N (nucleocapsid protein) antibody and Diazyme IgG). We demonstrate that the Roche S-antibody and Diazyme NAbs assays detected adaptive immune response in SARS-CoV-2 vaccinated individuals and the presence of SARS-CoV-2 PSV NAbs. The Roche S-antibody assay had an observed positive percent agreement (PPA) of 100% for individuals who received two doses of the Pfizer or Moderna vaccine. By contrast, the Roche N assay and Diazyme IgG assay did not detect vaccine adaptive immune responses. Our findings also indicate that the Diazyme NAbs assay correlates strongly with the levels of SARS-CoV-2 ID50 neutralization titers using the PSV Nab assay in vaccinated individuals.