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. 2020 Oct 30;22(10):e19152.
doi: 10.2196/19152.

Rapid Serological Assays and SARS-CoV-2 Real-Time Polymerase Chain Reaction Assays for the Detection of SARS-CoV-2: Comparative Study

Angelo Virgilio Paradiso #  1 , Simona De Summa #  2 , Daniela Loconsole  3 , Vito Procacci  4 , Anna Sallustio  5 , Francesca Centrone  3 , Nicola Silvestris  6   7 , Vito Cafagna  8 , Giuseppe De Palma  9 , Antonio Tufaro  9 , Vito Michele Garrisi #  8 , Maria Chironna #  3   4   5   10
Affiliations

Rapid Serological Assays and SARS-CoV-2 Real-Time Polymerase Chain Reaction Assays for the Detection of SARS-CoV-2: Comparative Study

Angelo Virgilio Paradiso et al. J Med Internet Res. .

Abstract

Background: Real-time polymerase chain reaction (RT-PCR) testing for the identification of viral nucleic acid is the current standard for the diagnosis of SARS-CoV-2 infection, but technical issues limit its utilization for large-scale screening. Serological immunoglobulin M (IgM)/IgG testing has been proposed as a useful tool for detecting SARS-CoV-2 exposure.

Objective: The objective of our study was to compare the results of the rapid serological VivaDiag test for SARS-CoV-2-related IgM/IgG detection with those of the standard RT-PCR laboratory test for identifying SARS-CoV-2 nucleic acid.

Methods: We simultaneously performed both serological and molecular tests with a consecutive series of 191 symptomatic patients. The results provided by a new rapid serological colorimetric test for analyzing IgM/IgG expression were compared with those of RT-PCR testing for SARS-CoV-2 detection.

Results: Of the 191 subjects, 70 (36.6%) tested positive for SARS-CoV-2 based on RT-PCR results, while 34 (17.3%) tested positive based on serological IgM/IgG expression. Additionally, 13 (6.8%) subjects tested positive based on serological test results, but also tested negative based on RT-PCR results. The rapid serological test had a sensitivity of 30% and a specificity of 89% compared to the standard RT-PCR assay. Interestingly, the performance of both assays improved 8 days after symptom appearance. After 10 days had passed since symptom appearance, the predictive value of the rapid serological test was higher than that of the standard molecular assay (proportion of positive results: 40% vs 20%). Multivariate analysis showed that age >58 years (P<.01) and period of >15 days after symptom onset (P<.02) were significant and independent factors associated with serological test positivity.

Conclusions: The rapid serological test analyzed in this study seems limited in terms of usefulness when diagnosing SARS-CoV-2 infection. However, it may be useful for providing relevant information on people's immunoreaction to COVID-19 exposure.

Keywords: COVID-19; RT-PCR; SARS-CoV-2; serological test.

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Conflict of interest statement

Conflicts of Interest: None declared.

Figures

Figure 1
Figure 1
Comparison of RT-PCR and VivaDiag results from a series of 191 subjects (P=.001). Compared to RT-PCR, VivaDiag had a sensitivity of 30%, specificity of 89%, accuracy of 67% (95% CI 60-74), and Cohen κ value of 0.21. RT-PCR: real-time polymerase chain reaction.
Figure 2
Figure 2
Bar plot depicting the distribution of the proportion of positive results from the VivaDiag serological test and those from RT-PCR testing for SARS-CoV-2 detection on oropharyngeal swab specimens according to time after symptom onset to test performance. RT-PCR: real-time polymerase chain reaction.
Figure 3
Figure 3
Bar plot depicting the distribution of the proportion of positive IgG and IgM VivaDiag test results according to time after symptom onset to test performance. IgG: immunoglobulin G; IgM; immunoglobulin M.
See this image and copyright information in PMC

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