Successful containment of a flight-imported COVID-19 outbreak through extensive contact tracing, systematic testing and mandatory quarantine: Lessons from Vietnam

Ha-Linh Quach; Ngoc-Anh Thi Hoang; Cong Khanh Nguyen; Quang Thai Pham; Cong Dinh Phung; Nhu Duong Tran; Quynh Mai Thi Le; Duy Nghia Ngu; Anh Tu Tran; Ngoc Quang La; Dai Quang Tran; Trong Tai Nguyen; Florian Vogt; Duc Anh Dang

doi:10.1016/j.tmaid.2021.102084

Successful containment of a flight-imported COVID-19 outbreak through extensive contact tracing, systematic testing and mandatory quarantine: Lessons from Vietnam

Travel Med Infect Dis. 2021 Jul-Aug:42:102084. doi: 10.1016/j.tmaid.2021.102084. Epub 2021 May 26.

Authors

Affiliations

¹ Department of Communicable Diseases Control, 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.
² Department of Communicable Diseases Control, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam. Electronic address: nck@nihe.org.vn.
³ Department of Communicable Diseases Control, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam; Institute of Preventive Medicine and Public Health, Hanoi Medical University, Hanoi, Viet Nam.
⁴ National Agency for Science and Technology Information, Ministry of Science and Technology, Hanoi, Viet Nam.
⁵ National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam.
⁶ Department of Communicable Diseases Control, National Institute of Hygiene and Epidemiology, Hanoi, Viet Nam.
⁷ Ha Noi University of Public Health, Hanoi, Viet Nam.
⁸ General Department of Preventive Medicine, Ministry of Health, Hanoi, Viet Nam.
⁹ Institute of Preventive Medicine and Public Health, Hanoi Medical University, Hanoi, Viet Nam.
¹⁰ 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.

Abstract

Background: The importation of SARS-CoV-2 through air travel poses substantial risks to generate new COVID-19 outbreaks. Timely contact tracing is particularly crucial to limit onwards transmission in settings without established community transmission.

Methods: We conducted an in-depth analysis of the response to a big flight-associated COVID-19 outbreak in Vietnam in March 2020 that involved contact tracing, systematic testing and strict quarantine up to third generation contacts.

Results: 183 primary contacts from the flight as well as 1000 secondary and 311 third generation contacts were traced, tested, and quarantined across 15 provinces across Vietnam. The protracted confirmation of the index case at 3 days and 19 h after arrival resulted in isolation/quarantine delays of 6.8 days (IQR 6.3-6.8) and 5.8 days (IQR 5.8-7.0) for primary and secondary cases, respectively, which generated 84.0 and 26.4 person-days of community exposure from primary and secondary cases, respectively. Nevertheless, only 5 secondary cases occurred.

Conclusions: A large flight-related COVID-19 cluster was successfully contained through timely, systematic and comprehensive public health responses despite delayed index case identification. Multiagency collaboration and pre-established mechanisms are crucial for low and middle income countries like Vietnam to limit community transmission after COVID-19 importation through air travel.

Keywords: Air travel; COVID-19; Case importation; Cluster containment; Contact tracing; Vietnam.

MeSH terms

COVID-19 / diagnosis*
COVID-19 / epidemiology
COVID-19 / prevention & control*
COVID-19 / transmission
COVID-19 Testing*
Contact Tracing*
Disease Outbreaks / statistics & numerical data*
Federal Government
Humans
Quarantine / legislation & jurisprudence*
SARS-CoV-2 / isolation & purification
Vietnam / epidemiology