Probable Causes and Risk Factors for Positive SARS-CoV-2 Testing in Recovered Patients: Evidence From Guangzhou, China

Lei Luo; Dan Liu; Zhoubin Zhang; Zhihao Li; Chaojun Xie; Zhenghe Wang; Zongqiu Chen; Peidong Zhang; Xiru Zhang; Yujie Zhang; Wenfang Zhong; Wenting Zhang; Pei Yang; Qingmei Huang; Weiqi Song; Hui Wang; Chen Mao

doi:10.3389/fmed.2021.684101

Probable Causes and Risk Factors for Positive SARS-CoV-2 Testing in Recovered Patients: Evidence From Guangzhou, China

Front Med (Lausanne). 2021 Jul 12:8:684101. doi: 10.3389/fmed.2021.684101. eCollection 2021.

Authors

Lei Luo¹, Dan Liu², Zhoubin Zhang¹, Zhihao Li², Chaojun Xie¹, Zhenghe Wang², Zongqiu Chen¹, Peidong Zhang², Xiru Zhang², Yujie Zhang², Wenfang Zhong², Wenting Zhang², Pei Yang², Qingmei Huang², Weiqi Song², Hui Wang¹, Chen Mao²

Affiliations

¹ Guangzhou Center for Disease Control and Prevention, Guangzhou, China.
² Department of Epidemiology, School of Public Health, Southern Medical University, Guangzhou, China.

Abstract

Some patients retested positive for SARS-CoV-2 following negative testing results and discharge. However, the potential risk factors associated with redetectable positive testing results in a large sample of patients who recovered from COVID-19 have not been well-estimated. A total of 745 discharged patients were enrolled between January 30, 2020, and September 9, 2020, in Guangzhou, China. Data on the clinical characteristics, comorbidities, drug therapy, RT-PCR testing, and contact modes to close contacts were collected. Patients who tested positive for SARS-CoV-2 after discharge were confirmed by guidelines issued by China. The repositive rate in different settings was calculated. Among 745 discharged patients, 157 (21.1%; 95% CI, 18.2-24.0%) tested repositive and the repositive rate was 16.8% (95% CI, 14.1-24.0%) for nasopharyngeal swabs and 9.7% (95% CI, 7.0-12.5%) for anal swabs. Among them, 55 (35.0%) were asymptomatic, 15 (9.6%) had mild symptoms, 83 (52.9%) had moderate symptoms, and 4 (2.6%) had severe symptoms at the first admission. The days from discharge to repositivity was 8.0 (IQR, 8.0-14.0). Most repositive patients were without clinical symptoms, and lymphocyte cell counts were higher than before being discharged. The likelihood of repositive testing for SARS-CoV-2 RNA was significantly higher among patients who were of younger age (OR, 3.88; 95% CI, 1.74-8.66, 0-17 years old), had asymptomatic severity (OR, 4.36; 95% CI, 1.47-12.95), and did not have clinical symptoms (OR, 1.89; 95% CI, 1.32-2.70, without fever). No other positive patients emerged within the families or close contacts of repositive patients. Our findings support prolonged but intermittent viral shedding as the probable cause for this phenomenon; we need to familiarize with the possibility that the virus will remain endemic.

Keywords: COVID-19; cohort study; discharged patients; repositive; risk factors.