A Comparative Study of Nine SARS-CoV-2 IgG Lateral Flow Assays Using Both Post-Infection and Post-Vaccination Samples

Abstract

Background: Since the SARS-CoV-2 pandemic, lateral flow assays (LFA) detecting specific antibodies have entered the market in abundance. Despite being CE-IVD-labeled, the antigenic compounds of the assays are often unknown, the performance characteristics provided by the manufacturer are often incomplete, and the samples used to obtain the data are not detailed. Objective: To perform a comparative evaluation of nine lateral flow assays to detect IgG responses against SARS-CoV-2. For the evaluation, a carefully designed serum panel containing post-infection samples and post-vaccination (both mRNA vaccine and inactivated virus vaccine) samples was used. Results: The sensitivity of the assays overall ranged from 9 to 90.3% and the specificity ranged from 94.2 to 100%. Spike protein-containing assays performed generally better than the assays with only nucleocapsid protein. The sensitivity of some assays was higher on post-infection samples, while other assays had a higher sensitivity to post-vaccination samples. Conclusion: A comparative approach in the verification of LFAs with an adequately designed serum panel enabled the identification of the antigens used in the assays. Sensitivities differed between post-infection and post-vaccination samples, depending on the assays used. This demonstrates that the verification of assays must be performed with samples representative of the intended use of the assay.

Evaluation of the performance of a lateral flow device for quantitative detection of anti-SARS-CoV-2 IgG

“…There are few studies assessing the SARS-CoV-2 immune response of samples from vaccinated individuals compared to those of infected individuals [8] , The conclusions of the studies by Salvagno et al [9] and Chuguza et al, recognized the need for booster vaccinations following a decline in antibody levels after 6 months. This is particularly important given the indication of protection from COVID-19 associated with [10] , as well as reports of reduction in risk of symptomatic infection in correlation with higher levels of immune markers to include anti-spike, anti-receptor binding domain and neutralising antibodies [11] .…”

An update on lateral flow immunoassay for the rapid detection of SARS-CoV-2 antibodies

“…It has also to be mentioned that even with centralized laboratory tests it has been difficult to compare cut-off values, since antibody titers are not harmonized according to the WHO International Standard for anti-SARS-CoV-2 immunoglobulin [101] . To meet these needs, research is ongoing to transform quantitative LFIAs to semi-quantitative tests, in which the intensity of the visual band can be correlated with the level of antibodies [102] , [103] . Also, studies correlating LFIAs results with the rate of protection would be useful.…”

“…Recently Mulder and co-workers analyzed nine different LFIAs, with target N, S or both proteins on samples from post-infected and post-vaccinated (mRNA and inactivated virus vaccines) individuals [102] . A great variability in the sensitivity of the tests has been reported.…”

Nanotechnology meets immunology towards a rapid diagnosis solution: the COVID-19 outbreak challenge

“…The clinical spectrum of COVID-19 ranges from asymptomatic infections and mild upper respiratory tract illnesses to severe viral pneumonia with respiratory failure, multiorgan failure, and death. 2 Thus, the World Health Organization declared the SARS-CoV-2 a global pandemic on March 11, 2020. 3 To date, two years later, there are already over 267.5 million confirmed COVID-19 cases and over 5.2 million deaths reported globally.…”