Correlation between a quantitative anti-SARS-CoV-2 IgG ELISA and neutralization activity.

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• Assessing protective immunity against SARS-CoV-2 requires understanding the correlation between binding and neutralizing antibodies.
• The EUROIMMUN Anti-SARS-CoV-2 QuantiVac ELISA (IgG) is a novel quantitative assay for detecting binding antibodies.

Purpose of the Study:

• To evaluate the correlation between the EUROIMMUN Anti-SARS-CoV-2 QuantiVac ELISA (IgG) and a microneutralization assay.
• To determine the utility of the QuantiVac ELISA in assessing functional antiviral immunity.

Main Methods:

• Analysis of 123 plasma samples from a COVID-19 outbreak study population.
• Utilized Spearman's correlation analysis to compare quantitative ELISA IgG levels with microneutralization assay titers.
• Preselected samples using semiquantitative anti-SARS-CoV-2 IgG testing.

Main Results:

• A strong positive correlation (r_s = 0.819, p < 0.0001) was observed between anti-S1 IgG levels and neutralizing antibody titers.
• The QuantiVac ELISA detected binding IgG in 86.2% of samples, while 72.4% showed neutralizing activity.
• High anti-S1 IgG levels had a 72.0% positive predictive value for high-titer neutralizing antibodies; low levels had a 90.8% negative predictive value.

Conclusions:

• The QuantiVac ELISA (IgG) is a reliable tool for measuring anti-SARS-CoV-2 IgG binding.
• Results strongly support the implementation of the QuantiVac ELISA for assessing protective immunity post-infection or vaccination.
• The assay effectively predicts the presence of neutralizing antibodies, crucial for characterizing antiviral immunity.