[Source: Clinical Infectious Diseases, full page: (LINK). Abstract, edited.]
The first 100 days of SARS-CoV-2 control in Vietnam
Quang Thai Pham, Maia A Rabaa, Huy Luong Duong, Quang Tan Dang, Dai Quang Tran, Ha-Linh Quach, Ngoc-Anh Thi Hoang, Cong Dinh Phung, Duy Nghia Ngu, Anh Tu Tran, Ngoc Quang La, My Phuc Tran, Chau Vinh, Cong Khanh Nguyen, Duc Anh Dang, Nhu Duong Tran, Guy Thwaites, H Rogier van Doorn, Marc Choisy, OUCRU COVID-19 Research Group
Clinical Infectious Diseases, ciaa1130, https://doi.org/10.1093/cid/ciaa1130
Published: 01 August 2020
One hundred days after SARS-CoV-2 was first reported in Vietnam on January 23rd, 270 cases were confirmed, with no deaths. We describe the control measures used by the Government and their relationship with imported and domestically-acquired case numbers, with the aim of identifying the measures associated with successful SARS-CoV-2 control.
Clinical and demographic data on the first 270 SARS-CoV-2 infected cases and the timing and nature of Government control measures, including numbers of tests and quarantined individuals, were analysed. Apple and Google mobility data provided proxies for population movement. Serial intervals were calculated from 33 infector-infectee pairs and used to estimate the proportion of pre-symptomatic transmission events and time-varying reproduction numbers.
A national lockdown was implemented between April 1st and 22nd. Around 200 000 people were quarantined and 266 122 RT-PCR tests conducted. Population mobility decreased progressively before lockdown. 60% (163/270) of cases were imported; 43% (89/208) of resolved infections remained asymptomatic for the duration of infection. The serial interval was 3·24 days, and 27·5% (95% confidence interval, 15·7%-40·0%) of transmissions occurred pre-symptomatically. Limited transmission amounted to a maximum reproduction number of 1·15 (95% confidence interval, 0·37-2·36). No community transmission has been detected since April 15th.
Vietnam has controlled SARS-CoV-2 spread through the early introduction of mass communication, meticulous contact-tracing with strict quarantine, and international travel restrictions. The value of these interventions is supported by the high proportion of asymptomatic and imported cases, and evidence for substantial pre-symptomatic transmission.
COVID-19, SARS-CoV-2, Vietnam, asymptomatic, epidemic control
Issue Section: Major Article
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© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
Keywords: SARS-CoV-2; COVID-19; Vietnam.