SARS-CoV-2 Antibody Responses Do Not Predict COVID-19 Disease Severity

Area of Science:

• Immunology
• Virology
• Diagnostic Assay Development

Background:

• Initial reports suggest adequate performance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology assays.
• Further studies are needed to interpret results and understand the impact of antibody levels on immunity and disease course.

Purpose of the Study:

• To evaluate the performance of a SARS-CoV-2 IgG assay.
• To investigate the correlation between antibody levels (IgG and IgM) and disease severity.

Main Methods:

• Tested 967 subjects for SARS-CoV-2 IgG antibodies using serology.
• Included suspected cases, healthy donors, rheumatic disease patients, and PCR-confirmed respiratory viral panel positive individuals.
• Assessed IgM antibodies in a subgroup of PCR-positive cases via proteome array.

Main Results:

• The SARS-CoV-2 IgG assay demonstrated 100% specificity and no cross-reactivity.
• Positive agreement with PCR was 83% for samples >14 days post-symptom onset.
• IgM was more frequently detected in cases <3 days from symptom onset.
• No association was found between IgG/IgM levels and disease severity.

Conclusions:

• The studied SARS-CoV-2 IgG assay is highly specific and reliable.
• Antibody levels (IgG and IgM) do not appear to predict disease severity in this patient cohort.