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Clinical Characteristics of Recovered COVID-19 Patients with Redetectable Positive SARS-CoV-2 RNA and the Associated Risk Factors
42 Pages Posted: 5 May 2020
More...Abstract
Background: The phenomenon of patients recovering from COVID-19 who tested positive for SARS-CoV-2 after discharge (redetectable as positive, RP) has been reported in several countries. The incidence rate and risk factors for being RP and the clinical course of COVID-19 in RP patients have not been well described.
Methods: This retrospective cohort study included all adult inpatients (≥18 years old) with laboratory-confirmed COVID-19 from Guangzhou Eighth People's Hospital — the only designated hospital for RP patients in Guangzhou. Observation started on Jan 20, 2020, with a final date of Mar 14, 2020 (the date the last RP patient was discharged). Demographic, clinical, treatment and serial laboratory data including the serial cycle threshold (Ct) values for viral RNA detection, outcome data, and chest computed tomographic (CT) scans, were extracted and compared between RP and non-RP (NRP) patients. We reported the incidence rate of being RP and the clinical course (both the first and second hospitalization) of COVID-19 in RP patients. Risk factors related to being RP in COVID-19 patients were explored using univariate and multivariate-adjusted logistic regression methods.
Findings: A total of 285 patients from Guangzhou Eighth People's Hospital were included in this study. All of patients were discharged, and by March 14, 27 (9·47%) discharged patients had tested positive for SARS-CoV-2 in their nasopharyngeal swab specimens again. The median duration from discharge to retesting positive was 7·0 days (IQR 5·0-8·0). Compared with the first hospitalization, RP patients were in better condition during rehospitalization, with milder clinical symptoms (number of asymptomatic patients: 17 [63%] vs 5 [19%]; p=0·013), lower viral load (median N gene Ct value: 37·5 vs 35·0; p=0·042), shorter length of stay (median length of stay: 7 days vs 18 days; p<0·0001) and improved pulmonary conditions (18 [67%] patients with lung improvement). Multivariate-adjusted logistic regression showed increasing odds of being RP in patients associated with a duration of positivity on nucleic acid testing >10 days during the first hospitalization (N gene: 5·82, 2·50-13·57; p<0·0001. ORF gene: 9·64, 3·91-23·73; p<0·0001) and a lower Ct value (ORF) in the third week of hospitalization (odds ratio, 0·69; 95% CI 0·50-0·95; p=0·022).
Interpretation: A nearly 10% incidence rate of being RP suggests that a large number of RP patients may appear globally, which deserves attention from other countries. The low efficiency of viral clearance during hospitalization can help clinicians assess the possibility of patients being RP at an early stage to reduce the risk of being RP and readmission. Concerning the constant repetition of virus in RP patients, their potential infectiousness still needs to be investigated in future studies.
Funding Statement: Open Project of Guangdong Provincial Key Laboratory of Tropical Disease Research.
Declaration of Interests: All authors declare no competing interests.
Ethics Approval Statement: The study was approved by the institutional ethics board of Guangzhou Eighth People's Hospital and the requirement for informed consent was waived by the ethics board.
Keywords: COVID-19, viral load, recovered patients, redetectable as positive, risk factors
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