Abstract
Objectives: To examine the relationship between antibody status and cycle threshold (Ct) values, the prognostic value of the latter for COVID-19 patients, and the inter-assay comparability of SARS-CoV-2 Ct values.
Methods: In 347 COVID-19 inpatients, SARS-CoV-2 Ct values (via reverse transcription-quantitative polymerase chain reaction) on admission were compared between 2 assays and correlated with the antibody response (in the course of the disease), the clinical course and the time since onset of symptoms.
Results: Ct values for 2 of 3 target genes showed significant differences between the 2 assays used (P=0.012 and P<0.0001). Ct values were significantly higher for antibody positive patients (P<0.0001) and positively correlated with the amount of time since onset of symptoms (R: 0.332-0.363; P<0.001). Patients with fatal outcomes showed higher viral loads than survivors (P<0.0001).
Conclusions: Ct values depend strongly on assay used and target gene examined and should not be used as quantitative values to guide therapeutic or diagnostic decisions. The inverse association between antibody status and viral load suggests that antibodies contribute to the elimination of the virus, independent of the outcome, which is influenced by the viral load on admission and might depend more strongly on other parts of the immune response.
Keywords: COVID-19; Ct value; RT-qPCR; SARS-CoV-2; anti-SARS-CoV-2 antibodies.
【저자키워드】 COVID-19, SARS-CoV-2, anti-SARS-CoV-2 antibodies, RT-qPCR, Ct value, 【초록키워드】 immune response, antibody, Antibody Response, diagnostic, outcome, virus, Elimination, polymerase chain reaction, anti-SARS-CoV-2 antibodies, RT-qPCR, Clinical course, Viral load, cycle threshold, qPCR, therapeutic, Ct value, reverse transcription, Admission, COVID-19 patients, association, Target genes, Ct values, comparability, independent of, target gene, Chain Reaction, Inpatients, Prognostic value, significant difference, significant differences, quantitative polymerase chain reaction, antibody status, survivor, independent, polymerase chain, quantitative values, Course, examined, the disease, onset of symptom, contribute, correlated, significantly higher, onset of symptoms, positive patient, the antibody response, positively correlated, quantitative value, 【제목키워드】 anti-SARS-CoV-2 antibody, incidence, Cycle threshold value, polymerase chain,