Corroboration of the Accuracy of the Biohit SARS-CoV-2 IgM/IgG LFA test kit
The human immune response to a COV/0-19 infection encompasses the host synthesis of anti-SARS-CoV-2 lgM antibodies that are detectable after about 5 to 7 days of infection which, in turn, is followed by an lgG antibody response after 10 plus days of infection. The selectivity and specificity of a SARS-CoV-2 lgM/lgG Antibody Test is most accurate eleven plus days after infection onset. Thus, detection of the immune response to a COVI 0-19 infection by an Antibody Assay may be inaccurate during early infection from days O to 7 During this same time period, RNA detectability by RT-qPCR is at best about 67%. This “window period” is best approached by using an orthogonal approach. Effective orthogonal algorithms are generally based on testing a patient sample with two tests, each with unique design characteristics (e.g., antigens or formats). This results in increasing detection or assessment accuracy. Such an approach would be exemplified by utilizing a Biohit SARS-CoV-2 lgM/lgG Antibody test and a RT-qPCR molecular study or a Biohit SARS-CoV-2 Antigen Assay.
2. Yale Study *Minteer C. et al. Multi-site Validation of a SARS-CoV-2 lgG/lgM Rapid Antibody Detection Kit (pre-publication), 2020. https://www.medrxiv.org/content/10.1101/2020.05.25.20112227v1. full.pdf(
In a recent study completed at Yale University in collaboration with four study sites in China, the Biohit lateral flow immunoassay (LFA) for detecting SARS-CoV-2 IgM and IgG antibodies was examined (1). Blood samples acquired from a cohort of 1892 SARS-CoV-2 patients and controls underwent assessment by the Biohit immunoassay. At Yale, a refined study protocol was utilized for study inclusion. Specifically, positive results from both ELISA (SARS-Cov-2 antibody detection) and viral detection by real time RT-PCR (RT-qPCR) were required for patient enrollment. The Biohit serologic studies of Yale patient samples collected after 14-days of symptoms demonstrated excellent findings. These results were a specificity of 97.6% for IgM, 100% for IgG, and sensitivities of 100% respectively for IgM, IgG and total antibodies (i.e., IgM plus IgG). These results are very similar to those promulgated by the kit manufacturer’s previously reported study of 40 patients with CoVID-19, 108 healthy individuals, and 78 patients with other respiratory infections (see the response to the last FAQ question and the web site’s Clinical Evaluation Report under the Resource heading). In this latter study, the specificity for IgM and IgG respectively was 99.5% and 100%; whereas, the selectivity for both IgM and IgG was 97.5%. Of note, in another study completed at the University of California at San Francisco (UCSF), an assessment and contrast of the results detected by 10 different LFA antibody kits were reported (2). Although different patient populations were tested, the Biohit SARS-CoV-2 IgM/IgG LFA test kit results reported in the Yale study demonstrate higher sensitivity values for IgG/IgM in patients with infection times greater than 11 days compared with the very best LFA and ELISA tests evaluated in the UCSF study. Furthermore, the specificity of the Biohit immunoassay was comparable to the best performing assays evaluated by the UCSF group. Thus, these results demonstrate that the use of the Biohit CoV-2 IgM/IgG LFA test kit is an excellent method for SARS-CoV-2 IgM/IgG detection.
- Minteer C. et al. Multi-site Validation of a SARS-CoV-2 IgG/IgM Rapid Antibody Detection Kit (pre-publication), 2020. https://www.medrxiv.org/content/10.1101/2020.05.25.20112227v1.full.pdf
- Whitman, J.D. et al. Test performance evaluation of SARSCoV-2 serological assays. medRxiv, 2020. https://www.medrxiv.org/content/10.1101/2020.04.25.20074856v2.full.pdf