Efficacy of POC Antibody Assays After COVID-19 Infection and Potential Utility for "Immunity Passports"

Akram Shalaby, MD; Hansini Laharwani, MD; John T. Bates, PhD; Patrick B. Kyle, PhD

Disclosures

Lab Med. 2022;53(3):262-265. 

In This Article

Abstract and Introduction

Abstract

Objective: Numerous manufacturers market lateral flow assays for the detection of SARS-CoV-2 antibodies, but there are many questions about the reliability and efficacy of these tests.

Materials and Methods: Serum specimens from 60 individuals were analyzed using 2 lateral flow antibody assays, an in-house enzyme-linked immunosorbent assay (ELISA), and the Abbott SARS-CoV-2 IgG chemiluminescent immunoassay.

Results: The BioMedomics and Premier Biotech lateral flow assays were positive for IgM in 73.3% and 70% and for IgG in 80% and 73.3% of specimens, respectively. The ELISA assay was positive for IgM and IgG in 73.3% and 86.7% of specimens from infected individuals, whereas the Abbott assay was positive in 80%. The specificities of the 4 assays ranged from 96.7% to 100% for IgM and from 93.3% to 100% for IgG.

Conclusion: Results of the 2 lateral flow assays were comparable to those of the ELISA and Abbott assays. Assay efficacy depended on length of time after SARS-CoV-2 infection.

Introduction

COVID-19, caused by the SARS-CoV-2 virus, rapidly spread globally and was declared a worldwide pandemic in March 2020. The gold standard test methodology for the diagnosis of SARS-CoV-2 infection involves real-time polymerase chain reaction (RT-PCR) of viral RNA collected via a nasopharyngeal swab.[1] The detection of antibodies formed in response to SARS-CoV-2 could be a useful methodology to safely return adults to the workplace and children to school. Given estimates of asymptomatic COVID-19 infections ranging from 16% to 30%,[2] antibody tests may help us understand how the epidemic has progressed and provide crucial information about the true mortality of the disease. Early data suggested that convalescent plasma infusion and antibody tests were used to identify potential plasma donors as a treatment option for patients with COVID-19.[3–5]

Some reservations exist regarding the accuracy of available antibody tests, which became evident when the United Kingdom determined that 1 million test kits purchased from China lacked sufficient accuracy and could not be used for testing.[6] In addition, not all point-of-care tests have been properly vetted, and the results of these assays may vary.[7] A study comparing the performance of 7 lateral-flow IgM/IgG assays found sensitivities ranging from 50% to 97.4% in specimens collected 14 to 25 days after symptom onset.[8] In the current study, we sought to evaluate 2 point-of-care assays manufactured for the detection of human antibodies to the SARS-CoV-2 virus by comparing them to an in-house enzyme-linked immunosorbent assay (ELISA) and a commercially available assay.

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