Clinical performance of a dual-target SARS CoV-2 antibody assay using sera from Ghana

During the pandemic, numerous serological tests for severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) have been developed. However, limited data exist on the clinical performance of these immunoassays with sera from Africa. The aim of this study was to determine the clinical performance characteristics of a lateral flow IgG antibody test using serum and plasma samples from Ghana. We assessed the performance of the COVID-19 Sero-NP/RBD test, a dual-target lateral flow assay designed to simultaneously detect IgG antibodies against the SARS-CoV-2 nucleoprotein (NP) and spike receptor-binding domain (RBD). Diagnostic sensitivity and specificity were determined using pre-pandemic plasma samples (N = 300) and samples from recovered COVID-19 patients with varying symptom severity (N = 308). Test performance was further analyzed in relation to antibody concentration. The combined detection of anti-RBD and anti-NP antibodies yielded a diagnostic sensitivity of 96.1% (95% CI: 94.1–98.4) and a specificity of 99.0% (95% CI: 97.1–99.8). Combined antigen detection significantly outperformed individual antigen targets (p < 0.001), with RBD-targeted responses demonstrating higher sensitivity than NP alone. Sensitivity declined with lower antibody titres, decreasing to 86.0% for samples with ≤ 25 BAU/mL and to 57.0% for those with ≤ 7.5 BAU/mL when either antigen was used alone. The COVID-19 Sero-NP/RBD lateral flow test demonstrated high accuracy in detecting past SARS CoV-2 infection in sera from Ghana. Dual-antigen targeting enhanced diagnostic sensitivity, particularly in individuals with low antibody titres. This assay may serve as a practical tool for assessing individual serostatus and monitoring population-level seroprevalence in Ghana and similar African settings.