of 40 pre-symptomatic and symptomatic cases

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Re-positive testing, clinical evolution and clearance of SARS-CoV-2 infection in Viet Nam Hoang et al

Supplementary Table 1. Public health interventions to prevent transmission from flights to Viet Nam, 2020

Starting date Actions

1 January Temperature screening^a for passengers from Hubei, China at all entry points (airport, sea, land) in Viet Nam

6 March Case finding and contact tracing for all passengers on flights with identified infected case(s) Mandatory health declaration for all inbound passengers from international flights

14 March SARS-CoV-2 testing at arrival and quarantine for passengers from the United Kingdom of Great Britain and Northern Ireland and all 26 countries in the Schengen Area

18 March Expanded SARS-CoV-2 testing upon arrival and quarantine for passengers from the United States, selected South-East Asian countries^b and Russia

21 March SARS-CoV-2 testing upon arrival and quarantine for all passengers from international flights regardless of place of departure

28 March All international flights halted

a Including both forehead temperature measurement and heat imaging.

b Brunei Darussalam, Cambodia, Indonesia, Lao People’s Democratic Republic, Malaysia, Myanmar, the Philippines, Singapore and Thailand.

a Combined symptoms at onset and during treatment/isolation.

b Cases could have more than one symptom.

Supplementary Table 2. Symptoms at onset and number of symptoms during infection

^a

of 40 pre-symptomatic and symptomatic cases

n %

Symptoms at onset^b

Cough 28 70

Fever 10 25

Sputum production 5 12.5

Sore throat 4 10

Headache 4 10

Fatigue 3 7.5

Nasal congestion 1 2.5

Diarrhoea 1 2.5

Chill 1 2.5

Total number of symptoms during infection

1 12 30

2 8 20

3 8 20

4 3 7.5

5 3 7.5

6+ 6 15

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Hoang et al Re-positive testing, clinical evolution and clearance of SARS-CoV-2 infection in Viet Nam

Supplementary Fig. 1. Methods of case detection

^a

of 50 cases in Viet Nam

a Methods of case detection included: 1) screening activities (i.e. mandatory testing and quarantine immediately upon international arrival); 2) case finding (i.e. epidemiological investigations); and 3) self-presenting at health facilities.

b All 16 local cases were close contacts of the 34 international passengers.

8 (23.5%) cases detected by screening activities 6 (75%)

symptomatic cases

2 (25%)

asymptomatic cases

7 (20.6%) cases detected by self-presenting 2 (28.6%) pre-

symptomatic cases

5 (71.4%) symptomatic cases 19 (55.9%) cases detected by case finding 9 (47.4%) pre-

symptomatic cases 34 (68%) international

passengers

16 (32%) local cases^b 50 COVID-19 cases

6 (31.6%) symptomatic cases

4 (21%) asymptomatic cases

16 (100%) cases detected by case finding 8 (50%) pre-

symptomatic cases

4 (25%) symptomatic cases

4 (25%) asymptomatic cases

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Re-positive testing, clinical evolution and clearance of SARS-CoV-2 infection in Viet Nam Hoang et al

1.00 Sur vival probability

Time in days Number at risk

Time in days 0.75

0.50 0.25

0.00 0 10 20 30 40 50

0 10 20 30 40 50

Supplementary Fig. 2. Cumulative probability of clearance of SARS-CoV-2 infection by time in days from symptom onset for 40 pre-symptomatic and symptomatic cases

The survival probability was estimated using the Kaplan-Meier estimator.