Evaluation of COVID-19 antibody response with using three different tests
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Published on: February 16, 2022
Özgür Appak1, Abdurrahman Gülmez2, Irmak Güzel3
1Department of Medical Microbiology, Division of Medical Virology, School of Medicine, Dokuz Eylul University, Izmir, Turkey.
Insights
This study evaluated COVID-19 antibody tests, finding that older age, male gender, and typical chest CT findings correlate with a stronger antibody response. Biochemical markers showed no significant association with antibody or RT-qPCR results.
Area of Science:
- Immunology and Infectious Diseases
- Diagnostic Assay Performance
- COVID-19 Research
Background:
- Evaluating the performance of commercial antibody assays for COVID-19 is crucial for accurate diagnosis and understanding immune response.
- Investigating factors influencing antibody detection, such as patient demographics and clinical findings, enhances diagnostic interpretation.
Purpose of the Study:
- To assess the performance of three distinct commercial antibody assays for detecting COVID-19 antibodies.
- To identify parameters, including chest CT results and biochemical markers, that correlate with the antibody response.
Main Methods:
- Compared three commercial assays (two rapid immunochromatographic, one ELISA IgG) for COVID-19 antibody detection.
- Utilized RT-qPCR for SARS-CoV-2 RNA detection from nasopharyngeal swabs.
- Retrospectively analyzed correlations between antibody results, RT-qPCR, chest CT findings, and biochemical parameters (CRP, D-dimer, procalcitonin).
Main Results:
- Rapid immunochromatographic tests showed 36.6% sensitivity and 100% specificity versus RT-qPCR; ELISA assay had 43.9% sensitivity and 95.7% specificity.
- Antibody positivity correlated with older age, male gender, and typical chest CT findings (odds ratio 13.62).
- Lower PCR Ct values were associated with increased antibody positivity; no significant link found with CRP, D-dimer, or procalcitonin.
Conclusions:
- Antibody response in COVID-19 patients is associated with male gender, older age, and typical chest CT findings.
- Lower viral load (indicated by lower PCR Ct values) correlates with detectable antibody responses.
- Commercial antibody assay performance varies, necessitating careful interpretation alongside clinical and molecular data.
Background And Objectives:
In this study, the performance of three different commercial antibody assays for COVID-19 was examined and parameters affecting the antibody response were investigated. The correlation of patients' chest CT results, procalcitonin, CRP, and D-dimer levels with the antibody response were retrospectively evaluated.
Materials And Methods:
COVID-19 antibodies were detected by three commercially available assays in each patient. Two of the assays were rapid immunochromatographic tests and - one was an ELISA-based IgG assay. SARS-CoV-2 RNA was tested by "COVID-19 RT-qPCR Detection Kit" using nasopharyngeal swab samples. The results of antibody tests were compared with each other, RT-qPCR, Biochemical parameters and chest CT findings.
Results:
RT-qPCR was positive in 46.6% (41/88) of the evaluated patients among which 77.3% (68/88) were healthcare workers. Seventeen (41.4%) of viral RNA positive patients had a positive antibody result with at least two assays. Both of the rapid immunochromatographic tests had identical sensitivity of 36.6% and specificity of 100%, compared to RT-qPCR assay; while the sensitivity of the ELISA based Euroimmune test was 43.9%, and the specificity was 95.7%. The sensitivity and specificity of the immunochromatographic tests were 75% and 100% respectively, compared to ELISA test result. There was a correlation between antibody positivity and old age and male gender. The presence of typical chest CT findings increased the antibody positivity 13.62 times. Antibody positivity was also increased with the decrease in Ct value of the PCR assay. There was no significant relationship between the biochemical parameters (CRP, D-dimer and procalcitonin values) and the antibody or RT-qPCR results.
Conclusion:
There was a correlation between antibody response and male gender, older age, presence of symptoms, typical chest CT findings and low PCR-Ct value.
