Comparative performance of COVID-19 serology testing.

Area of Science:

• Immunology
• Infectious Diseases
• Clinical Diagnostics

Background:

• The COVID-19 pandemic spurred the development of numerous diagnostic assays for SARS-CoV-2.
• While molecular and antigen tests have established roles, the clinical utility of serology for assessing immunity remains unclear.
• Current recommendations do not advise serology for immunity assessment.

Purpose of the Study:

• To evaluate the performance of four commercially available laboratory-based COVID-19 serology assays (Assays A-D).
• To compare positive percent agreement (PPA) and negative percent agreement (NPA) across different assays.
• To analyze antibody concentrations in relation to patient status (hospitalized vs. non-hospitalized) and vaccination.

Main Methods:

• A pragmatic, observational study was conducted using remnant patient samples.
• Samples from PCR-confirmed SARS-CoV-2 positive patients and vaccinated/unvaccinated individuals were tested.
• PPA, NPA, and antibody concentrations were calculated and compared between assays and populations.

Main Results:

• All four assays demonstrated high PPA (95.8-99.2%) and 100% NPA at 5-12 weeks post-PCR positivity.
• Higher antibody concentrations were observed in hospitalized patients compared to non-hospitalized patients for Assays A, B, and C (P < 0.001).
• Assays A and C showed higher antibody concentrations in individuals who received two vaccine doses.

Conclusions:

• Performance metrics (PPA and NPA) varied among the evaluated COVID-19 serology assays.
• Assays A and C exhibited superior performance, yielding higher PPA and NPA.
• These assays also detected greater antibody concentrations following vaccination, suggesting their potential for assessing immune response.