Demonstrating Clinical Performance of the Elecsys Anti-SARS-CoV-2 Anti-Nucleocapsid Immunoassay Using Real-World Data to Support Regulatory Decision-Making in the USA

Abstract Introduction Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a global public health concern. Anti-nucleocapsid (anti-N) serology is a key tool for identifying prior infection and supporting population-level surveillance. This study evaluated the clinical performance of the Elecsys® Anti-SARS-CoV-2 Anti-N immunoassay on the Cobas® e 601/602 immunoassay analyzer using real-world data from patients with polymerase chain reaction (PCR)-confirmed symptomatic SARS-CoV-2 infection. The study aimed to provide data which, along with clinical study data, supported the transition from Emergency Use Authorization of the assay to full clearance in the USA. Methods We conducted a retrospective review of electronic medical records and laboratory information system data from patients who presented to Columbia University Irving Medical Center from March 2020 to March 2021. Eligible participants were symptomatic, unvaccinated individuals with PCR-confirmed SARS-CoV-2 infection who subsequently underwent serologic testing. Serologic results were categorized by days post symptom onset (DPSO): 0–7, 8–14, and ≥ 15 days. To avoid repeated measures, only the first serologic result per patient within each DPSO category was included. The primary endpoint was positive percent agreement (PPA) for nonimmunocompromised individuals tested at ≥ 15 DPSO, with a prespecified acceptance threshold of ≥ 90%. Results A total of 585 serologic tests from 567 patients (77, 45, and 463 samples, in DPSO categories of 0–7, 8–14, and ≥ 15 days, respectively) were evaluated. Among nonimmunocompromised individuals with samples collected ≥ 15 DPSO (N = 285), the PPA was 96.49% (95% confidence interval 93.66%, 98.08%), fulfilling the predefined acceptance criterion. PPA was also consistent across demographic subgroups, supporting the generalizability of the findings. Conclusions This study demonstrates the feasibility of generating robust clinical evidence for regulatory purposes using real-world data. The clinical performance of the Elecsys Anti-SARS-CoV-2 immunoassay was confirmed using data collected under routine conditions during the pandemic, complementing data from controlled clinical studies and contributing to informed regulatory decision-making.