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Lateral flow immunoassays (LFIA) for antibody detection represent cost-effective and user-friendly tools for serology assessment. This study evaluated a new LFIA prototype developed with a recombinant chimeric antigen from the spike/S and nucleocapsid/N proteins to detect anti-SARS-CoV-2 IgG antibodies. The evaluation of LFIA sensitivity and specificity used 811 serum samples from 349 hospitalized, SARS-CoV-2 RT-qPCR positive COVID-19 patients, collected at different time points and 193 serum samples from healthy controls. The agreement between ELISA results with the S/N chimeric antigen and LFIA results was calculated. The LFIA prototype for SARS-CoV-2 using the chimeric S/N protein demonstrated 85% sensitivity on the first week post symptoms onset, reaching 94% in samples collected at the fourth week of disease. The agreement between LFIA and ELISA with the same antigen was 92.7%, 0.827 kappa Cohen value (95% CI 0.765 – 0.889). Further improvements are needed to standardize the prototype for whole blood use. The inclusion of the novel chimeric S+N antigen in the COVID-19 IgG antibody LFIA demonstrated optimal agreement with results from a comparable ELISA, highlighting the prototype's potential for accurate large-scale serologic assessments in the field in a rapid and user-friendly format.
Fogaça et al. (Thu,) studied this question.