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

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

Ha-Linh Quach  1 , Ngoc-Anh Thi Hoang  1 , Cong Khanh Nguyen  2 , Quang Thai Pham  3 , Cong Dinh Phung  4 , Nhu Duong Tran  5 , Quynh Mai Thi Le  5 , Duy Nghia Ngu  6 , Anh Tu Tran  6 , Ngoc Quang La  7 , Dai Quang Tran  8 , Trong Tai Nguyen  9 , Florian Vogt  10 , Duc Anh Dang  5
Affiliations

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

Ha-Linh Quach et al. Travel Med Infect Dis. 2021 Jul-Aug.

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.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Fig. 1
Fig. 1
Contact tracing strategy for primary contacts of VN54 flight in Vietnam.
Fig. 2
Fig. 2
Testing and quarantine strategy for traceable primary, secondary, and third generation contacts of VN54 flight in Vietnam.
Fig. 3
Fig. 3
Time course for contact tracing of primary, secondary, and third generation contacts of VN54 flight in Vietnam.
Fig. 4
Fig. 4
Temporal sequence of exposure, symptom onset and isolation for all primary and secondary cases of VN54 flight in Vietnam.
Fig. 5
Fig. 5
A. Geographical distribution of primary cases and contacts of VN54 flight in Vietnam. B. Geographical distribution of secondary cases and contacts of VN54 flight in Vietnam.
See this image and copyright information in PMC

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