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Updated: Nov 1, 2025
A Rapid, Multiplex Dual Reporter IgG and IgM SARS-CoV-2 Neutralization Assay for a Multiplexed Bead-Based Flow Analysis System
Published on: April 6, 2021
Performance assessment of SARS-CoV-2 IgM & IgG ELISAs in comparison with plaque reduction neutralization test
Ruta Kulkarni1, Shubham Shrivastava1, Harshad P Patil1
1Departments of Communicable Diseases, Interactive Research School for Health Affairs, Bharati Vidyapeeth Medical College, Pune, Maharashtra, India.
Insights
Performance of SARS-CoV-2 IgM and IgG ELISAs was assessed. Inbios-IgM-ELISA showed high sensitivity and specificity for COVID-19 diagnosis, while IgG tests are suitable for assessing past virus exposure in serosurveys.
Area of Science:
- Immunology
- Virology
- Epidemiology
Background:
- The COVID-19 pandemic, caused by SARS-CoV-2, necessitates reliable diagnostic and serologic tools.
- Performance assessment of IgM and IgG ELISAs is crucial for patient management and understanding viral spread.
Purpose of the Study:
- To evaluate the diagnostic performance of commercial SARS-CoV-2 IgM and IgG ELISAs.
- To determine the utility of these ELISAs for patient diagnosis and sero-epidemiologic investigations.
Main Methods:
- Serum/plasma samples from 180 COVID-19 patients and 90 healthy donors were tested.
- Two IgM ELISAs and four IgG ELISAs were compared against the plaque reduction neutralization test (PRNT).
- An indigenous inactivated virus-based ELISA (IRSHA-IgG-ELISA) was also evaluated.
Main Results:
- Inbios-IgM-ELISA demonstrated high sensitivity (93.6%) and specificity (97.8%) relative to PRNT, improving detection after two weeks of illness.
- Among IgG ELISAs, Inbios-IgG-ELISA showed the highest sensitivity (83.2%), with all IgG tests exhibiting high specificity and suitability for serosurveys.
- Sensitivity for both IgM and IgG assays improved over time post-infection.
Conclusions:
- SARS-CoV-2 IgM ELISAs can supplement molecular diagnosis but do not replace it.
- Available SARS-CoV-2 IgG ELISAs are appropriate for serosurveys to assess previous infection exposure.
- Accurate serologic testing is vital for tracking pandemic dynamics and immunity.
Background & Objectives:
Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) continues to be a devastating pandemic. This study was aimed at performance assessment of SARS-CoV-2 IgM and IgG ELISAs, and investigation of their utility for patient diagnosis and sero-epidemiologic investigations.
Methods:
Serum/plasma samples from COVID-19 patients or asymptomatic contacts (n=180) and healthy donors (n=90) were tested in parallel using two commercial IgM ELISAs (Erbalisa and Inbios), and four IgG ELISAs (Kavach, Euroimmun, Erbalisa and Inbios) along with an indigenous β-propiolactone inactivated virus-based ELISA (IRSHA-IgG-ELISA). Plaque reduction neutralization test (PRNT) was used as reference test.
Results:
Among 180 COVID-19 patients, 125 tested positive by PRNT. Inbios-IgM-ELISA showed sensitivity (Se)/specificity (Sp)/positive predictive value (PPV)/negative predictive value (NPV) of 93.6/97.8/98.4/94.4 per cent in relation to PRNT, and performed better than Erbalisa-IgM-ELISA (Se: 48%, Sp: 95.6%, PPV: 95.2%, NPV: 65.2%). During the first week of disease, only 47.4 per cent of the COVID-19 patients tested IgM positive by Inbios-IgM-ELISA, detection improving at two weeks and beyond (~86-100%). Among IgG tests, Inbios-IgG-ELISA ranked first in terms of sensitivity (83.2%), followed by IRSHA (64.8%), Euroimmun (64%), Erbalisa (57.6%) and Kavach (56%) tests. For all IgG tests, sensitivity improved during the third (73.9-95.7%) and fourth week (100%) of illness. The specificity (96.7-100%) and PPV (96.2-100%) of all IgG tests were high; NPV ranged between 71.9 and 87.1 per cent with Inbios-IgG-ELISA scoring highest.
Interpretation & Conclusions:
Our results show that IgM detection by the current, most sensitive ELISAs cannot replace molecular diagnosis, but may aid as a supplement test. The available IgG tests are suitable for serosurveys for the assessment of previous virus exposure.
