Clinical usefulness of fully automated chemiluminescent immunoassay for quantitative antibody measurements in COVID‐19 patients

Abstract

Background

Since December 2019 we have been in the battlefield with a new threat to the humanity, known as SARS‐CoV‐2, which causes COVID‐19, characterized by viral pneumonia. It may be asymptomatic or cause various symptoms, ranging from flu like symptoms to ARDS and eventually death. At present, the only reliable test for COVID‐19 diagnosis is RT‐qPCR. Assessing the immune response against SARS‐CoV‐2 could increase the detection sensitivity of infected population. Hereby, we report the performances of a fully automated chemiluminescent immunoassay (CLIA) on 276 serum samples.

Methods

One hundred samples obtained from COVID‐19 negative subjects (COVID‐19 free) were analyzed to evaluate diagnostic specificity of antibody (Ab) detection. Thereafter, 176 samples obtained from 125 patients with confirmed COVID‐19 (COVID‐19 patients) were selected to assess the diagnostic sensitivity of the CLIA. All samples were analyzed on MAGLUMI ^TM 800 platform.

Results

All COVID‐19 free samples had Ab levels below the cut‐off values. Hence, the diagnostic specificity was estimated at 100% (95%CI= 96.3‐100.0; PPV= 100%). By the 18 ^th day from the onset of symptoms we reached to an optimal diagnostic sensitivity (more than 95.0 %) In fact, the diagnostic sensitivity increased over time and between 15 to 25 days after symptoms onset, reached to 95.5% (95% CI= 84.9‐99.2).

Conclusion

The new automated CLIA analyzer appeared to be a robust and reliable method to measure specific Ab against COVID‐19 at a high throughput. Our data suggest that combining Ab and nucleic acid detection could increase the diagnostic sensitivity.

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