Re-positive testing, clinical evolution and clearance of infection: results from COVID-19 cases in isolation in Viet Nam

Authors

  • Ngoc-Anh Hoang Department of Epidemiology, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; National Centre for Epidemiology and Population Health, Research School of Population Health, College of Health and Medicine, Australian National University, Canberra, Australia https://orcid.org/0000-0002-5675-9396
  • Thai Quang Pham Department of Epidemiology, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; School of Preventive Medicine and Public Health, Hanoi Medical University, Hanoi, Viet Nam https://orcid.org/0000-0002-3796-6162
  • Ha-Linh Quach Department of Epidemiology, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; National Centre for Epidemiology and Population Health, Research School of Population Health, College of Health and Medicine, Australian National University, Canberra, Australia https://orcid.org/0000-0001-7160-8329
  • Khanh Cong Nguyen Department of Epidemiology, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; National Centre for Epidemiology and Population Health, Research School of Population Health, College of Health and Medicine, Australian National University, Canberra, Australia https://orcid.org/0000-0002-3775-9139
  • Samantha Colquhoun National Centre for Epidemiology and Population Health, Research School of Population Health, College of Health and Medicine, Australian National University, Canberra, Australia https://orcid.org/0000-0002-6750-1147
  • Stephen Lambert National Centre for Epidemiology and Population Health, Research School of Population Health, College of Health and Medicine, Australian National University, Canberra, Australia https://orcid.org/0000-0002-2709-193X
  • Huy Luong Duong Department of Epidemiology, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam https://orcid.org/0000-0003-3548-8416
  • Dai Quang Tran General Department of Preventive Medicine, Ministry of Health, Hanoi, Viet Nam
  • Cong Dinh Phung National Agency for Science and Technology Information, Ministry of Science and Technology, Viet Nam
  • Nhu Duong Tran National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam https://orcid.org/0000-0002-9159-1103
  • Duy Nghia Ngu Department of Epidemiology, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Anh Tu Tran Department of Epidemiology, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam
  • Hue Bich Thi Nguyen National Hospital of Tropical Diseases, Hanoi, Viet Nam
  • Duc-Anh Dang National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam https://orcid.org/0000-0002-2380-2431
  • Florian Vogt National Centre for Epidemiology and Population Health, Research School of Population Health, College of Health and Medicine, Australian National University, Canberra, Australia; The Kirby Institute, University of New South Wales, Sydney, NSW, Australia

DOI:

https://doi.org/10.5365/wpsar.2021.12.4.857

Abstract

Objectives: Asymptomatic infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and test re-positivity after a negative test have raised concerns about the ability to effectively control the coronavirus disease 2019 (COVID-19) pandemic. We aimed to investigate the prevalence of COVID-19 asymptomatic and pre-symptomatic infections during the second wave of COVID-19 in Viet Nam, and to better understand the duration of SARS-CoV-2 infection and the dynamics between the evolution of clinical symptoms and SARS-CoV-2 test positivity among confirmed COVID-19 cases.

Methods: We conducted a cohort analysis on the first 50 confirmed cases during the second COVID-19 wave in Viet Nam using clinical, laboratory and epidemiological data collected from 9 March to 30 April 2020. Kaplan-Meier estimates were used to assess time to clearance of SARS-CoV-2 infection, and log-rank tests were used to explore factors related to time to SARS-CoV-2 infection clearance.

Results: Most cases (58%) had no typical signs or symptoms of COVID-19 at the time of diagnosis. Ten cases (20%) were re-positive for SARS-CoV-2 during infection. Eight cases (16%) experienced COVID-19 symptoms after testing negative for SARS-CoV-2. The median duration from symptom onset until clearance of infection was 14 days (range: 6–31); it was longer in re-positive and older patients and those with pre-existing conditions.

Conclusion: Asymptomatic and pre-symptomatic infections were common during the second wave of COVID-19 in Viet Nam. Re-positivity was frequent during hospitalization and led to a long duration of SARS-CoV-2 infection.

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Published

13-12-2021

How to Cite

1.
Hoang N-A, Pham TQ, Quach H-L, Nguyen KC, Colquhoun S, Lambert S, Duong HL, Tran DQ, Phung CD, Tran ND, Ngu DN, Tran AT, Nguyen HBT, Dang D-A, Vogt F. Re-positive testing, clinical evolution and clearance of infection: results from COVID-19 cases in isolation in Viet Nam. Western Pac Surveill Response J [Internet]. 2021 Dec. 13 [cited 2026 Mar. 22];12(4). Available from: https://ojs.wpro.who.int/ojs/index.php/wpsar/article/view/857

Issue

Vol. 12 No. 4 (2021): October ‒ December

Section

COVID-19: Original Research

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