COVID-19 Antibody Tests: An Overview

Abstract

Novel coronavirus (nCoV) first emerged in Hubei province of China in December 2019. The virus initially known as 2019-nCoV was renamed to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) by the International Committee on Taxonomy of Viruses. The associated disease is known as coronavirus disease 2019 (COVID-19). As the COVID-19 pandemic has unfolded, interest has grown in antibody testing as a way to measure how far the infection has spread and to identify individuals who may be immune. Molecular diagnostic tests like polymerase chain reaction are developed rapidly, however they are not able to fulfill all the requirements of an epidemic reaction. Hence, to complement molecular diagnostic tests, serology tests emerged as a vital aspect of the overall response by confirming the presence of antibodies during the early stage of the infection. Antibody tests help in assessing herd immunity, data about the ongoing phase of infection, identifying potential donors for convalescent plasma therapy, etc. This review currently focuses on giving an overview about the antibody tests in SARS-CoV-2 infections.

SARS-CoV-2 Detection Methods

“…These are serological tests that analyze blood or serum samples to detect specific SARS-CoV-2 antibodies. These tests will inform if one person has been infected with COVID-19 by detecting the presence of either immunoglobulin G (IgG) or immunoglobulin M (IgM) [7]. These antibodies are directed against the Spike (S) and Nucleocapside (N) proteins and have their highest levels 2 weeks after symptoms onset in the case of IgM and 3 weeks after symptom onset for IgG, the latter also providing long-term immunity.…”

Recent updates on liposomal formulations for detection, prevention and treatment of coronavirus disease (COVID-19)

“…Antigen testing by lateral flow assay of rapid antigen tests generated the fastest result within 15 min after saliva or nasal sample was loaded, making it the most accessible COVID-19 diagnostic test used at the moment ( Mahmoudinobar et al, 2021 , Peto et al, 2021 ). Antibody levels against COVID-19 can also be quantified using the blood samples of patients and serological enzyme-linked immunosorbent assay (ELISA) ( Ravi et al, 2021 ). A summary of the diagnostic tests for COVID-19 approved by the WHO is shown in Fig.…”

Development of a high-sensitivity and short-duration fluorescence in situ hybridization method for viral mRNA detection in HEK 293T cells

“…The COVID-19 Antibody (IgG and IgM) Test is a blood test that determines whether an individual has previously had a SARS-CoV-2 infection by the detection of antibodies against specific viral proteins ( Lindsay et al., 2021 ; Ravi et al., 2021 ). As the first antibody to appear during infection, IgM is often utilized as a marker of acute infection.…”

“…With the development of infection, the level of IgG increases, and the concentration of IgM gradually decreases, possibly disappearing after a certain time. Compared with the RT-PCR, the antibody test is more straightforward, faster, and more efficient (often showing strong sensitivity and specificity; Ravi et al., 2021 ). However, this test also has certain limitations.…”

“…The first is the possibility of a false-negative result. For example, if the test is performed too early following an infection, a negative result may be obtained ( Ravi et al., 2021 ). The second limitation is that specific IgM and IgG tests also suffer from false positives arising ( Lindsay et al., 2021 ).…”