Clinical characteristics of the recovered COVID-19 patients with re-detectable positive RNA test

Jianghong An; Xuejiao Liao; Tongyang Xiao; Shen Qian; Jing Yuan; Haocheng Ye; Furong Qi; Chengguang Shen; Yang Liu; Lifei Wang; Xiaoya Cheng; Na Li; Qingxian Cai; Fang Wang; Jun Chen; Yingxia Liu; Yunfang Wang; Feng Zhang; Yang Fu; Xiaohua Tan; Lei Liu; Zheng Zhang

The underlying mechanisms underlying RP occurrence remain unclear. The possible reasons argued by a large number of experts are related to several virological, immunological and sampling methodological factors. Virologically, the false negatives [21] , viral residual [12] , intermittent viral release [12] and viral distribution [22, 23] are usually considered to be major factors. Our data support the notion that the false negatives using commercial kit may partially account for the RP, because the kits had only 30%-50% positive rate of detection [23, 24] . In 24 of various samples from RP patients, RNA was detected to be negative for both N gene and ORF1b gene at several days after their re-admission to the hospital using commercial kit, whose lower limit of detection (LOD) was relatively high (500 copies/ml). However, using a more sensitivity Sherlock kit with an LOD of 100 copies/ml [25] , 75% of samples were detected to be positive for S gene and 41.6% for ORF genes, thus leading to half of positive subjects present within RP patients with undetectable RNA using commercial kit in their hospitalization. By contrast, among 8 samples from NRP patients, none was detected to be positive using either Sherlock or commercial kit. However, in a sample confirmed by SRAS-CoV-2 sequencing, the Sherlock tested it as positive (data not shown). Therefore, future study should improve both the sensitivity and specificity of detection kit, All rights reserved. No reuse allowed without permission. the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.