Asymptomatic and Presymptomatic Transmission of 2019 Novel Coronavirus (COVID-19) Infection: An Estimation from a Cluster of Confirmed Cases in Ho Chi Minh City, Vietnam

26 Pages Posted: 22 Jun 2020 Last revised: 7 Jul 2020

See all articles by Cristina Valencia

Cristina Valencia

Global Outbreak Alert & Response Network

Luong Quang

Pasteur Institute Ho Chi Minh City

Mark Handcock

University of California - Los Angeles

Dung Nguyen

Ho Chi Minh Provincial Center for Disease Control

Quan Doan

Pasteur Institute Ho Chi Minh City

Thinh Viet Nguyen

Pasteur Institute Ho Chi Minh City

Nga Le

Ho Chi Minh Provincial Center for Disease Control

Than Truong

Ho Chi Minh Provincial Center for Disease Control

Hien Do

World Health Organization

Satoko Otsu

World Health Organization

Tuan Le

World Health Organization

Quang Pham

Pasteur Institute Ho Chi Minh City

Thuong Nguyen

Pasteur Institute Ho Chi Minh City

Phan Lan

Pasteur Institute Ho Chi Minh City

Linh Le

World Health Organization

Date Written: June 16, 2020

Abstract

Background
The rapid increase in the number of coronavirus disease 2019 (COVID-19) cases worldwide has raised concerns of viral transmission from individuals displaying no or delayed clinical symptoms. We quantified the transmission potential of asymptomatic, presymptomatic and symptomatic cases using surveillance data from a bar gathering in Ho Chi Minh City, Vietnam.

Methods
Between March 14 and April 25, 2020, we collected demographic, clinical and laboratory information of all COVID-19 confirmed cases and contacts from a bar gathering. We applied a Bayesian framework to estimate the proportions of asymptomatic, presymptomatic and symptomatic cases and transmissions with posterior modes and 90% credible intervals (CrI). Using Go.Data, we mapped chains of transmission and estimated the basic reproduction number (R_0).

Findings
Of the 298 individuals attending the bar gathering on March 14, 2020, 13 tested positive for SARS-CoV-2. Another 6 tested positive from 4466 contacts further traced. The proportions asymptomatic, presymptomatic, and symptomatic were 0·43 (90% CrI 0·26−0·60), 0·35 (90% CrI 0·20−0·52) and 0·22 (90% CrI 0·09−0·37), respectively. The proportion of asymptomatic, presymptomatic and symptomatic transmissions were 0·35 (90% CrI 0·16−0·68), 0·53 (90% CrI 0.21−0.77), and 0·04 (90% CrI 0·02−0·26), respectively. The cluster-specific R0 was 2·52 (90% CrI 1·65−4·88). The bar constituted 68%, workplace 21%, and household 11% of transmissions.

Interpretations
We demonstrated using statistical models on surveillance data that high of asymptomatic and presymptomatic transmission of COVID-19 occurred in a Vietnam cluster. Detecting and isolating presymptomatic and asymptomatic cases will be an important control measure as movement restrictions are lifted.

Funding
None

Note: Funding: None.

Conflict of Interest: We declare no competing interests.

Ethical Approval: The study was undertaken as required by national legislation for outbreak investigation and response. All epidemiological investigations were conducted in accordance to the MOH’s Decision Promulgating Interim guidance on COVID-19 surveillance, prevention and control. 963 / QD-BYT.

Keywords: Novel coronavirus (COVID-19), asymptomatic, presymptomatic, transmission, contact tracing, Go.Data, Vietnam

Suggested Citation

Valencia, Cristina and Quang, Luong Chan and Handcock, Mark and Nguyen, Dung Tri and Doan, Quan and Nguyen, Thinh Viet and Le, Nga Hong and Truong, Than-Lan and Do, Hien and Otsu, Satoko and Le, Tuan and Pham, Quang Duy and Nguyen, Thuong Vu and Lan, Phan Trong and Le, Linh-Vi, Asymptomatic and Presymptomatic Transmission of 2019 Novel Coronavirus (COVID-19) Infection: An Estimation from a Cluster of Confirmed Cases in Ho Chi Minh City, Vietnam (June 16, 2020). Available at SSRN: https://ssrn.com/abstract=3630119 or http://dx.doi.org/10.2139/ssrn.3630119

Cristina Valencia (Contact Author)

Global Outbreak Alert & Response Network ( email )

Avenue Appia
Geneva, 1202
Switzerland

Luong Chan Quang

Pasteur Institute Ho Chi Minh City ( email )

167 Pasteur, Phường 8, Quận 3,
Ho Chi Minh
Vietnam

Mark Handcock

University of California - Los Angeles ( email )

405 Hilgard Avenue
Box 951361
Los Angeles, CA 90095
United States

HOME PAGE: http://www.stat.ucla.edu/~handcock

Dung Tri Nguyen

Ho Chi Minh Provincial Center for Disease Control ( email )

61 Au Duong Lan, District 8
Ho Chi Minh City
Vietnam

Quan Doan

Pasteur Institute Ho Chi Minh City ( email )

167 Pasteur, Phường 8, Quận 3,
Ho Chi Minh
Vietnam

Thinh Viet Nguyen

Pasteur Institute Ho Chi Minh City ( email )

167 Pasteur, Phường 8, Quận 3,
Ho Chi Minh
Vietnam

Nga Hong Le

Ho Chi Minh Provincial Center for Disease Control ( email )

61 Au Duong Lan, District 8,
Ho Chi Minh City
Vietnam

Than-Lan Truong

Ho Chi Minh Provincial Center for Disease Control ( email )

61 Au Duong Lan, District 8
Ho Chi Minh City
Vietnam

Hien Do

World Health Organization ( email )

20 Avenue Appia
Geneva 27, CH-1211
Switzerland

Satoko Otsu

World Health Organization ( email )

304 Kim Ma St., Ba Dinh Dist
Hanoi
Vietnam

Tuan Le

World Health Organization ( email )

304 Kim Ma St., Ba Dinh Dist
Hanoi, CH-1211
Vietnam

Quang Duy Pham

Pasteur Institute Ho Chi Minh City ( email )

167 Pasteur, Phường 8, Quận 3,
Ho Chi Minh
Vietnam

Thuong Vu Nguyen

Pasteur Institute Ho Chi Minh City ( email )

167 Pasteur, Phường 8, Quận 3,
Ho Chi Minh
Vietnam

Phan Trong Lan

Pasteur Institute Ho Chi Minh City ( email )

167 Pasteur, Phường 8, Quận 3,
Ho Chi Minh
Vietnam

Linh-Vi Le

World Health Organization ( email )

P.O. Box 2932
Manila, 1000
Philippines

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