Clinical applications of detecting IgG, IgM, or IgA antibody for the diagnosis of COVID-19: A meta-analysis and systematic review

Highlights

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  The investigated positive results provided mark heterogeneity of sensitivity.

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  Diagnosing COVID-19 with either IgM + or IgG + presents a favorable diagnostic accuracy.

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  The sensitivity of antibody test might be improved by prolonged testing time.

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  IgA might be a surrogate providing a better diagnostic accuracy compared to IgG or IgM.

Abstract

Background

Coronavirus disease 2019 is a global pandemic. Serological antibody test is one important diagnostic method increasingly used in the clinic, although its clinical application is still under investigation.

Methods

We conducted a meta-analysis to compare the diagnostic performances of severe acute respiratory syndrome coronavirus 2 specific antibody tests in COVID-19 patients. Test results analyzed included (1) IgM-positive but IgG-negative (IgM ⁺IgG-), (2) IgG-positive but IgM-negative (IgG ⁺IgM-), (3) both IgM and IgG-positive (IgM ⁺IgG ⁺), (4) IgM-positive without IgG information (IgM ⁺IgG ^+/-), (5) IgG-positive without IgM information (IgG ⁺IgM ^+/-), (6) either IgM or IgG-positive (IgM ⁺ or IgG ⁺), and (7) IgA-positive (IgA ⁺).

Results

Sixty-eight studies were included. The pooled sensitivities of IgM ⁺IgG-, IgG ⁺IgM-, IgM ⁺IgG ⁺, IgM ⁺IgG ^+/-, IgG ⁺IgM ^+/-, and IgM ⁺ or IgG ⁺ were 6%, 7%, 53%, 68%, 73%, and 79% respectively. The pooled specificity ranged from 98% to 100%. The IgA ⁺ had a pooled sensitivity of 78%, but a relatively low specificity of 88%. Tests conducted two weeks after symptom onset provided improved diagnostic accuracy. Chemiluminescence immunoassay and detection of S protein as the antigen could offer a more accurate diagnostic result.

Discussion

Our findings support the supplemental role of serological antibody tests in COVID-19 diagnosis. However, their capacity to diagnose COVID-19 early in the disease course could be limited.