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Asymptomatic patients and asymptomatic phases of Coronavirus Disease 2019 (COVID-19): a population-based surveillance

Xueying Zheng1, Sihui Luo1, Yong Sun2

  • 1The First Affiliated Hospital of USTC, Division of Life Science and Medicine, University of Science and Technology of China, Hefei 230001, China.

National Science Review
|October 22, 2021
PubMed

Insights

Asymptomatic patients and those with weak transmissibility represented a small fraction of COVID-19 cases. Viral RNA negativity post-recovery is crucial for de-isolation, with follow-up recommended.

Area of Science:

  • Epidemiology
  • Infectious Diseases
  • Public Health

Background:

  • Understanding the transmission dynamics and clinical characteristics of COVID-19 is crucial for effective public health strategies.
  • Identifying asymptomatic and presymptomatic cases is vital for controlling viral spread.

Purpose of the Study:

  • To investigate the proportion and characteristics of asymptomatic COVID-19 patients.
  • To analyze the viral shedding dynamics and recovery patterns in confirmed COVID-19 cases.

Main Methods:

  • Population-based surveillance identifying 307 confirmed COVID-19 cases from extensive screening and contact tracing.
  • Clinical assessment of initial symptoms and monitoring of viral nucleic acid negativity post-recovery.

Main Results:

  • Only 5.54% of confirmed COVID-19 patients were asymptomatic upon initial assessment, with low detection rates among close contacts.
  • The median interval from symptom remission to viral RNA negativity was 5.0 days.
  • A small percentage (4.56%) of patients had re-detectable viral RNA after discharge, highlighting potential for prolonged shedding.

Conclusions:

  • Asymptomatic and presymptomatic individuals constitute a minor proportion of COVID-19 cases.
  • Viral RNA negativity is a necessary criterion for patient de-isolation.
  • Post-discharge follow-up is recommended to monitor for viral RNA re-detection.

Keywords:
COVID-19SARS-CoV-2asymptomaticepidemiologypublic healthsurveillance

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