COMPARATIVE SENSITIVITY OF ELISA VS. LATERAL FLOW ASSAYS IN COVID-19 ANTIBODY DETECTION

Abstract

Background: Reliable serological testing remains crucial in identifying prior exposure to SARS-CoV-2, especially in post-infection scenarios. Enzyme-linked immunosorbent assay (ELISA) and lateral flow assay (LFA) are widely used serological methods, yet differences in their diagnostic performance require further exploration to guide their optimal use.

Objective: To compare the diagnostic sensitivity, specificity, and overall performance of ELISA and lateral flow immunoassays in detecting SARS-CoV-2 antibodies in post-infection individuals.

Methods: A prospective, comparative study was conducted over eight months at a tertiary care diagnostic center. A total of 142 participants were enrolled, including 100 PCR-confirmed COVID-19 recovered patients and 42 pre-pandemic control subjects. Serum samples were analyzed using standardized ELISA kits and WHO-approved LFA devices to detect SARS-CoV-2-specific IgG and IgM antibodies. Outcome measures included sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy. Cohen’s kappa and ROC curve analysis were used for agreement and diagnostic performance assessment. Statistical analysis was performed using SPSS v26.

Results: ELISA demonstrated higher sensitivity (94.0%) and specificity (98.0%) compared to LFA (78.0% and 90.5%, respectively). ELISA showed a PPV of 97.9%, NPV of 94.2%, and overall accuracy of 96.5%, whereas LFA had 86.7%, 82.1%, and 84.5%, respectively. Agreement between ELISA and RT-PCR was strong (k = 0.89, AUC = 0.96), while LFA showed moderate agreement (k = 0.71, AUC = 0.84).

Conclusion: ELISA outperformed lateral flow assays in serological detection of SARS-CoV-2 antibodies post-infection. These findings support ELISA as the preferred diagnostic tool in clinical and epidemiological settings requiring high accuracy.