RESUMO
Background: Limited commercial LFA assays are available to provide a reliable quantitative measurement of the total binding antibody units (BAU/mL) against the receptor-binding domain of the SARS-CoV-2 spike protein (S-RBD). Aim: This study aimed to evaluate the performance of the fluorescence LFA FinecareTM 2019-nCoV S-RBD test along with its reader (Model No.: FS-113) against the following reference methods: (i) the FDA-approved GenScript surrogate virus-neutralizing assay (sVNT); and (ii) three highly performing automated immunoassays: BioMérieux VIDAS®3, Ortho VITROS®, and Mindray CL-900i®. Methods: Plasma from 488 vaccinees was tested by all aforementioned assays. Fingerstick whole-blood samples from 156 vaccinees were also tested by FinecareTM. Results and conclusions: FinecareTM showed 100% specificity, as none of the pre-pandemic samples tested positive. Equivalent FinecareTM results were observed among the samples taken from fingerstick or plasma (Pearson correlation r = 0.9, p < 0.0001), suggesting that fingerstick samples are sufficient to quantitate the S-RBD BAU/mL. A moderate correlation was observed between FinecareTM and sVNT (r = 0.5, p < 0.0001), indicating that FinecareTM can be used for rapid prediction of the neutralizing antibody (nAb) post-vaccination. FinecareTM BAU results showed strong correlation with VIDAS®3 (r = 0.6, p < 0.0001) and moderate correlation with VITROS® (r = 0.5, p < 0.0001) and CL-900i® (r = 0.4, p < 0.0001), suggesting that FinecareTM can be used as a surrogate for the advanced automated assays to measure S-RBD BAU/mL.
RESUMO
The currently authorized mRNA COVID-19 vaccines, Pfizer-BNT162b2 and Moderna-mRNA-1273, offer great promise for reducing the spread of the COVID-19 by generating protective immunity against SARS-CoV-2. Recently, it was shown that the magnitude of the neutralizing antibody (NAbs) response correlates with the degree of protection. However, the difference between the immune response in naïve mRNA-vaccinated and previously infected (PI) individuals is not well studied. We investigated the level of NAbs in naïve and PI individuals after 1 to 26 (median = 6) weeks of the second dose of BNT162b2 or mRNA-1273 vaccination. The naïve mRNA-1273 vaccinated group (n = 68) generated significantly higher (~2-fold, p ≤ 0.001) NAbs than the naïve BNT162b2 (n = 358) group. The P -vaccinated group (n = 42) generated significantly higher (~3-fold; p ≤ 0.001) NAbs levels than the naïve-BNT162b2 (n = 426). Additionally, the older age groups produced a significantly higher levels of antibodies than the young age group (<30) (p = 0.0007). Our results showed that mRNA-1273 generated a higher NAbs response than the BNT162b2 vaccine, and the PI group generated the highest level of NAbs response regardless of the type of vaccine.
