Emerging Microbes and Infections (Jan 2020)

Viral RNA level, serum antibody responses, and transmission risk in recovered COVID-19 patients with recurrent positive SARS-CoV-2 RNA test results: a population-based observational cohort study

  • Chao Yang,
  • Min Jiang,
  • Xiaohui Wang,
  • Xiujuan Tang,
  • Shisong Fang,
  • Hao Li,
  • Le Zuo,
  • Yixiang Jiang,
  • Yifan Zhong,
  • Qiongcheng Chen,
  • Chenli Zheng,
  • Lei Wang,
  • Shuang Wu,
  • Weihua Wu,
  • Hui Liu,
  • Jing Yuan,
  • Xuejiao Liao,
  • Zhen Zhang,
  • Xiaolu Shi,
  • Yijie Geng,
  • Huan Zhang,
  • Huanying Zheng,
  • Min Wan,
  • Linying Lu,
  • Xiaohu Ren,
  • Yujun Cui,
  • Xuan Zou,
  • Tiejian Feng,
  • Junjie Xia,
  • Ruifu Yang,
  • Yingxia Liu,
  • Shujiang Mei,
  • Baisheng Li,
  • Zhengrong Yang,
  • Qinghua Hu

DOI
https://doi.org/10.1080/22221751.2020.1837018
Journal volume & issue
Vol. 9, no. 1
pp. 2368 – 2378

Abstract

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ABSTRACTManaging recovered COVID-19 patients with recurrent-positive SARS-CoV-2 RNA test results is challenging. We performed a population-based observational study to characterize the viral RNA level and serum antibody responses in recurrent-positive patients and evaluate their viral transmission risk. Of 479 recovered COVID-19 patients, 93 (19%) recurrent-positive patients were identified, characterized by younger age, with a median discharge-to-recurrent-positive length of 8 days. After readmission, recurrent-positive patients exhibited mild (28%) or absent (72%) symptoms, with no disease progression. The viral RNA level in recurrent-positive patients ranged from 1.8 to 5.7 log10 copies/mL (median: 3.2), which was significantly lower than the corresponding values at disease onset. There are generally no significant differences in antibody levels between recurrent-positive and non-recurrent-positive patients, or in recurrent-positive patients over time (before, during, or after recurrent-positive detection). Virus isolation of nine representative specimens returned negative results. Whole genome sequencing of six specimens yielded only genomic fragments. 96 close contacts and 1,200 candidate contacts of 23 recurrent-positive patients showed no clinical symptoms; their viral RNA (1,296/1,296) and antibody (20/20) tests were negative. After full recovery (no longer/never recurrent-positive), 60% (98/162) patients had neutralizing antibody titers of ≥1:32. Our findings suggested that an intermittent, non-stable excretion of low-level viral RNA may result in recurrent-positive occurrence, rather than re-infection. Recurrent-positive patients pose a low transmission risk, a relatively relaxed management of recovered COVID-19 patients is recommended.

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