Antibody Responses to SARS-CoV-2 in Patients of Novel Coronavirus Disease 2019
31 Pages Posted: 3 Mar 2020More...
Background: The novel coronavirus SARS-CoV-2 is a newly emerging virus. The antibody response in infected patient remains largely unknown, and the clinical values of antibody testing have not been fully demonstrated.
Methods: A total of 173 patients with confirmed SARS-CoV-2 infection were enrolled. Their serial plasma samples (n = 535) collected during the hospitalization period were tested for total antibodies (Ab), IgM and IgG against SARS-CoV-2 using immunoassays. The dynamics of antibodies with the progress and severity of disease was analyzed.
Findings: Among 173 patients, the seroconversion rate for Ab, IgM and IgG was 93.1% (161/173), 82.7% (143/173) and 64.7% (112/173), respectively. Twelve patients who had not seroconverted were those only blood samples at the early stage of illness were collected. The seroconversion sequentially appeared for Ab, IgM and then IgG, with a median time of 11, 12 and 14 days, respectively. The presence of antibodies was < 40% among patients in the first 7 days of illness, and then rapidly increased to 100.0%, 94.3% and 79.8% for Ab, IgM and IgG respectively since day 15 after onset. In contrast, the positive rate of RNA decreased from 66.7% (58/87) in samples collected before day 7 to 45.5% (25/55) during days 15 to 39. Combining RNA and antibody detections significantly improved the sensitivity of pathogenic diagnosis for COVID-19 patients (p < 0.001), even in early phase of 1-week since onset (p = 0.007). Moreover, a higher titer of Ab was independently associated with a worse clinical classification (p = 0.006).
Interpretation: The antibody detection offers vital clinical information during the course of SARS-CoV-2 infection. The findings provide strong empirical support for the routine application of serological testing in the diagnosis and management of COVID-19 patients.
Funding Statement: This study was supported by National Key R&D Program of China (SQ2020YFC080015), and the Science and Technology Major Project of Shenzhen, Fujian (2020YZ0106), Xiamen (3502Z2020YJ01) and Bill & Melinda Gates Foundation.
Declaration of Interests: The authors declare no competing interests.
Ethics Approval Statement: This study was reviewed and approved by the Medical Ethical Committee of Shenzhen Third People’s Hospital (approval number 2020-0018). Written informed consent was obtained from each enrolled patient.
Keywords: SARS-CoV-2; COVID-19; Antibody; Immunoassay; IgM; Diagnosis; Serology; Disease severity; Sensitivity
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