This is an online COVID-19 pre-publication manuscript which has been submitted to WPSAR. Pre-publication manuscripts are preliminary reports and have not been peer-reviewed. They should not be regarded as conclusive,
guide clinical practice/health-related behavior, or be reported in news media as established information.
Title: OUTBREAK OF COVID-19: IMPACT OF INTENSIVE COMMUNITY-LEVEL CONTROL 1
MEASURES 2
Short Title: CONTROL MEASURES FOR COVID-19 IN VIET NAM 3
Authors: Tran Nhu Duong1, Le Thi Quynh Mai1, Nguyen Tran Hien1, Ngu Duy Nghia1, Nguyen 4
Trong Khoa2, Nguyen Hai Tuan1, Tran Anh Tu1, Ngo Huy Tu1, Hoang Vu Mai Phuong1, Dang 5
Duc Anh1 6
1National Institute of Hygiene and Epidemiology, Ministry of Health, Hanoi, Vietnam; 2Agency 7
of Health Examination and Treatment, Ministry of Health, Hanoi, Vietnam 8
9
Corresponding author and contact details:
10
Dang Duc Anh MD, PhD 11
National Institute of Hygiene and Epidemiology 12
1 Yersin Street 13
Hanoi 100000, Viet Nam 14
Email: dda@nihe.org.vn 15
+84 (0) 90 322 9425 16
+84 (0)24 3821 3241 17
18
2 Abstract:
19
Objective: In January 2020, Vietnam experienced its first imported cases of COVID-19, a 20
respiratory infection caused by a novel coronavirus (SARS-CoV-2). Our objective was to 21
prevent further transmission in Viet Nam and share lessons learned for other communities and 22
countries.
23
Methods: Active case finding and contact tracing were performed. Cases were residents of 24
Vinh Phuc Province with detection of SARS-CoV-2 by real-time reverse transcriptase PCR.
25
Contacts were individuals with whom cases had had contact during the 14 days before 26
symptom onset or a positive test in the cases. We implemented extensive control measures, 27
including the quarantining of an entire community.
28
Results: We identified 11 laboratory-confirmed cases, 147 suspected cases, and over 600 29
contacts during our investigation. Eight cases were among women and the median age was 29 30
years. All survived. Onset of symptoms of the first case was four days after returning from 31
Wuhan. All subsequent cases were identified through contact tracing. Close contacts of cases 32
were quarantined at a local clinic converted into an inpatient unit and quarantine center while 33
contacts not considered to be close were quarantined at a military school. Ultimately, a 34
community of 10,000 individuals was quarantined for three weeks. No further cases were 35
detected.
36
Discussion: We identified an outbreak of COVID-19 associated with returning travelers from 37
Wuhan, China. Despite limited resources, our efforts to institute aggressive controls were 38
successful in interrupting transmission of SARS-CoV-2.
39
3 Keywords: COVID-19; active case finding; contact tracing; public health; epidemiology; Viet 40
Nam 41
Introduction:
42
In December 2019, a novel coronavirus emerged from Wuhan, China, in association with 43
cases of severe pneumonia, originally thought to be connected to a seafood market [1]. Since 44
then, the novel coronavirus has been named SARS-CoV-2 because of its close similarity to the 45
coronavirus that caused SARS in 2003 [2]. Coronavirus disease 2019 (COVID-19) has spread 46
to numerous countries outside of China and has been declared a global pandemic and a public 47
health emergency of international concern.
48
In the absence of vaccines and therapeutics, isolation, quarantine, and social distancing 49
remain the only tools currently available to mitigate spread of SARS-CoV-2. Vietnam shares a 50
1200km border with China, previously had multiple direct flights from Wuhan, and has had 51
long-standing cultural and business exchanges with China, all of which have increased the risk 52
of importation of SARS-CoV-2 into Vietnam.
53
In November 2019, eight Vietnamese workers traveled to Wuhan. In mid-January, these 54
workers returned to Vietnam, leading to the first importation of SARS-CoV-2 into northern 55
Vietnam. Our objectives were to describe the epidemiology of these COVID-19 infections so 56
that appropriate control measures could be implemented rapidly. We aimed to prevent further 57
transmission elsewhere in Vietnam. In this manuscript, we also share some key lessons 58
learned.
59 60
4 Methods:
61
Setting 62
Vinh Phuc province has a population of 1,092,400 people with an area of 1.37 square 63
kilometers. Binh Xuyen is one of seven districts and includes 13 communes of approximately 64
10,000 people each. Vinh Phuc is approximately 51 kilometers from Hanoi, the capital of 65
Vietnam and home to eight million people. In November 2019, eight Vietnamese employees of 66
an automobile parts manufacturing company traveled to Wuhan, China to participate in a two- 67
month training program. All eight employees returned to Vietnam on January 17, 2020, in time 68
for the annual Lunar New Year (Tet) holiday. Seven of these employees were residents of Binh 69
Xuyen district.
70
Epidemiologic investigation and laboratory methods 71
We defined cases of COVID-19 infection according to Vietnam Ministry of Health guidelines in 72
place at the time of our investigation. Specifically, suspected cases of COVID-19 infection 73
were residents of Vinh Phuc province with fever and cough, with or without shortness of 74
breath, and either 1) history of visiting Wuhan, China during the 14 days before onset of illness 75
or 2) close contact (within 2 meters) with confirmed or suspected cases from January 17 76
through March 3, 2020. Confirmed cases were residents of Vinh Phuc province with a positive 77
laboratory test for SARS-CoV-2 during study period, with or without symptoms.
78
We performed contact tracing by interviewing all seven Vinh Phuc residents who returned from 79
Wuhan. We requested information about their close contacts, including healthcare contacts, 80
family members, co-workers, friends, neighbors, other social contacts, and traveling 81
companions, e.g., individuals with whom they shared cars. We interviewed all close contacts to 82
5 identify those with symptoms such as fever, cough, fatigue, and difficulty breathing. We
83
collected oropharyngeal swabs from all suspected cases and all close contacts, including 84
those without symptoms.
85
We conducted descriptive epidemiologic analysis by characterizing all cases in terms of 86
demographics, household structure, travel history, and potential exposures.
87
We collected oropharyngeal swabs from suspected cases and their contacts. We placed the 88
swabs into viral transport media immediately after collection and transported them to the 89
National Institute of Hygiene and Epidemiology (NIHE), the public health agency of the 90
Vietnam Ministry of Health that is responsible for 28 provinces in the north of Vietnam, within 91
24 hours. We performed real-time reverse-transcriptase–polymerase-chain-reaction (rRT- 92
PCR) for SARS-CoV-2 as described elsewhere [3].
93
Public health response and control measures 94
The field response was led by the Vinh Phuc Provincial Center for Disease Control (CDC) with 95
support from NIHE. We deployed five trained doctors to each of the 13 commune health 96
stations of Binh Xuyen district (65 doctors total). We trained an additional 168 healthcare 97
workers from the district and commune levels on case investigation, contact tracing, and 98
proper wear of personal protective equipment (PPE). We implemented national response 99
guidelines developed by the Vietnam Ministry of Health at the direction of the National Steering 100
Committee on the Prevention and Control of COVID-19.
101
Based on the descriptive epidemiology, we implemented a series of control measures (Table 102
1). First, the Vinh Phuc cases described here were the first suspected cases in the north of 103
6 Vietnam. Therefore, they were referred to the National Hospital for Tropical Diseases, a tertiary 104
care hospital in Hanoi, for isolation, and clinical management.
105
Second, we implemented aggressive isolation procedures in Vinh Phuc. We converted the 106
Quang Ha Polyclinic, an outpatient clinic of Binh Xuyen district, into an inpatient isolation 107
facility for secondary cases. We divided the facility into six sections, one each for laboratory- 108
confirmed cases, suspected cases pending test results, family members of confirmed cases, 109
symptomatic patients whose first COVID-19 test was negative but who required 14 days of 110
observation, those who had recovered fully from COVID-19, and suspected cases and close 111
contacts testing positive for influenza and other respiratory viruses. We performed temperature 112
and symptom checks twice daily. For those with any symptoms, we performed temperature 113
and symptom checks four times per day. Staff at the polyclinic provided clinical management, 114
infection prevention and control, disinfection, and reporting services.
115
Third, we converted a local military school to a quarantine center for close contacts who were 116
not family members of cases. Beds were placed one to two meters apart. Meals were served 117
within each room free of charge and each contact received a daily monetary allowance. All 118
contacts were required to wear masks at all times. Soap and water as well as alcohol-based 119
hand rub were provided in each room and hand hygiene was strongly encouraged before and 120
after all meals and after using toilets. Each toilet was shared by two rooms. Disinfection of 121
hallways with chloramine B was performed whenever suspected cases were transferred from 122
the quarantine center to the Polyclinic. Waste was separated into potentially contaminated 123
waste (e.g., masks and tissues) and all other waste. All staff wore complete sets of personal 124
protective equipment, including whole body suits, gloves, eye protection, and surgical masks.
125
We performed temperature and symptom checks twice daily and recorded the findings on a 126
7 standard form. We collected oropharyngeal specimens for laboratory testing twice from each 127
contact under quarantine, once on day two and once on day 14 before discharge. We 128
delivered risk communication messages to all contacts under quarantine each day, reminding 129
them about the disease, to follow the regulations of the quarantine center, to avoid large 130
groups, to stay in their rooms, to wash hands regularly, and to notify staff of any symptoms. All 131
vehicles entering and exiting the military school campus were disinfected daily with chloramine 132
B, including those cars transporting suspected cases to the Quang Ha Polyclinic. All 133
discharged contacts remained under home isolation for one more week.
134
Fourth, because community cases were identified in Son Loi commune, we worked with local 135
authorities to impose a quarantine of the entire commune of 10,645 residents on the night of 136
February 13. We established eight quarantine stations on February 13 with four more 137
established on February 14. Police and members of the military staffed each quarantine station 138
which were inspected regularly by independent monitoring teams. Quarantine stations 139
remained in operation until March 3. Residents of Son Loi were permitted to leave for work or 140
other purposes but they were required to register at quarantine stations, informing local 141
authorities regarding when they would return. Visitors were only permitted to deliver supplies 142
(e.g., food, water) to the quarantine stations from which they would be collected and distributed 143
in the commune. Gatherings such as festivals and weddings were prohibited.
144
Fifth, teams of village healthcare workers and community or inter-family representatives 145
performed daily house-to-house health checks, including temperature measurements of all 146
household members and delivery of risk communication messages, for the 21-day period of 147
the quarantine. Each household was provided with a thermometer so that symptomatic family 148
members could have their temperature assessed and reported to village health workers at any 149
8 time. Two ambulance cars were always on duty in the commune. A mobile x-ray unit was 150
established at the Son Loi commune health station, a capacity not ordinarily available at most 151
commune health stations in Vietnam. Merchandise and vehicles entering and exiting Son Loi 152
were inspected and disinfected with chloramine B. Shops with fixed prices were established in 153
each of the six hamlets of Son Loi so that residents could purchase staples such as rice, 154
noodles, meat, and vegetables. Risk communication messages were delivered three times 155
each day via loudspeakers throughout the commune.
156
Finally, a team from Vietnam’s National Steering Committee for COVID-19 Prevention and 157
Control was deployed to direct and monitor all control activities for the duration of the 158
investigation and quarantine.
159
Ethical Considerations: This investigation was approved by the Institutional Review Board of 160
Pasteur Institute of Ho Chi Minh City, the organization with oversight of the national research 161
protocol for COVID-19.
162
Results:
163
Epidemiology 164
Between January 30 and February 12, 2020, we identified 11 cases of COVID-19 in Vinh Phuc 165
province (Table 3, Figure 1). Five of these cases occurred among workers returning from 166
Wuhan (imported cases) with the remaining six being close contacts (secondary cases) of the 167
imported cases. Eight were women and the median age of all cases was 29 years. Onset of 168
symptoms of the first case was on January 21, 2020, four days after returning from Wuhan.
169
Subsequent cases were all identified through contact tracing and regular follow up. Notably, all 170
six of the secondary cases could be linked either directly or indirectly to case 2. All cases 171
9 recovered clinically and were discharged following two negative PCR tests of upper respiratory 172
specimens (Table 2).
173
We identified 99 suspected cases in 13 communes of Binh Xuyen district over the following 12 174
days (Table 3). All 99 tested negative for SARS-CoV-2. For all cases (suspected and 175
confirmed), we found a total of 214 close contacts, all of whom were quarantined at the Quang 176
Ha Polyclinic (39) and military school (95) and an additional (80) contacts of these close 177
contacts, all of whom were quarantined at home. One contact, the father of case 2, developed 178
sore throat and fatigue while quarantined at the military school. He was immediately 179
transferred to the Quang Ha Polyclinic and a specimen collected was subsequently positive by 180
PCR. Twenty-two staff from the Vinh Phuc Center for Disease Control, the provincial 181
department of health, and military health workers provided services at the quarantine center.
182
No secondary cases were identified among healthcare workers in the Quang Ha Polyclinic or 183
among staff at the military school quarantine center.
184
Control measures 185
Over the course of our investigation, we observed several effects of our control measures 186
(Table 4). Through our case-finding, we observed a decrease in the number of days that cases 187
spent in the community before being hospitalized, with 0-7 (median 2) days for the five 188
imported cases and from -1 to +2 (median 0.5) days for the six secondary cases. With fewer 189
days in the community, cases had fewer opportunities to interact with contacts. We, therefore, 190
observed a reduction in the total number of contacts for each case (median 42 contacts per 191
case for the five imported cases compared to 10.5 cases per contact for the six secondary 192
cases).
193 194
10 Discussion:
195
Our investigation revealed rapid, person-to-person transmission of SARS-CoV-2 in a small 196
community in northern Vietnam. Given the intensity of transmission, especially surrounding the 197
household of case 2, this cluster had the potential to be much larger than it was. Indeed, 198
importation of cases into other countries has led to larger and more rapid increases in cases 199
transmitted throughout communities [4,5]. Our description of the aggressive public health 200
measures taken in Vinh Phuc go beyond previous summaries [6] and may prove useful to 201
other countries and communities striving to prevent widespread community transmission.
202
The interventions that we implemented were feasible in a short time because Vietnam adopted 203
a top-to-bottom whole-of-government approach. To lead and coordinate the government’s 204
response, a National Steering Committee on Prevention and Control of COVID-19 was 205
established on January 30, 2020. This committee, chaired by Deputy Prime Minister Vu Duc 206
Dam, meets at least three times weekly and includes all sectors of government, including 207
health, transportation, aviation, education, science, military, police, foreign affairs, and others.
208
Guidelines are issued several times each week and directly from this committee, with the 209
intention that all provinces and healthcare facilities will closely follow. Within the Ministry of 210
Health, technical expertise is devolved to the sub-national but multi-province level, so that field 211
investigations that cross provincial lines can be readily coordinated. Laboratory capacity is also 212
devolved so that, currently, approximately 57 laboratories throughout Viet Nam can perform 213
rtRT-PCR.
214
At the local level, we observed improvements in disease control not only in terms of the 215
eventual interruption of transmission but also in terms of our operations. For example, as our 216
contact tracing improved over the course of our investigation, the time to identify new cases 217
11 decreased. Concurrently, the opportunity for those cases to interact with community members, 218
i.e., the opportunity to have more contacts, also decreased. The speed with which public 219
health authorities identify and quarantine contacts is especially important in light of recent 220
information about asymptomatic and pre-symptomatic transmission of SARS-CoV-2 [1–3]. In 221
our experience, as the speed of our response increased, the associated workload decreased 222
as reflected in the number of contacts that required follow up. This was an important lesson for 223
us and one that we hope others can incorporate into their own public health response.
224
The quarantine imposed around Son Loi commune was implemented quickly, removed after a 225
pre-determined period, and maintained with minimal disruption to the lives of the residents.
226
Similar measures were implemented in Taiwan in 2003 in response to SARS [4] and more 227
recently in response to COVID-19 in Singapore [1]. Recent evidence suggests that public 228
policies that increase compliance with community mitigation strategies are necessary for 229
reducing community transmission [5]. When first implemented, large-scale quarantine of 230
communities can be highly disruptive. However, if they can be implemented quickly and at a 231
smaller scale, that disruption can be minimized and, importantly, disease transmission is more 232
likely to be contained. In Son Loi commune, the quarantine was implemented for no longer 233
than necessary, the rational was clear, and sufficient supplies were available to support 234
residents [6].
235
Our investigation took place at a time when the national public health response in Vietnam was 236
still developing. This created several challenges. For example, at the time that the employees 237
returned from Wuhan, there was no national or international guidance on how to detect or 238
manage asymptomatic cases. We, therefore, had to adopt what we believed was sensible 239
public health practice: assume that asymptomatic cases could transmit SARS-CoV-2 and 240
12 isolate them as if they were infectious. Laboratory testing was also not readily available, so we 241
often erred on the side of isolation and quarantine, knowing that suspected cases and contacts 242
may have to wait several days for test results. Our investigation began near the time of the 243
annual Lunar New Year (Tet) holiday, the largest holiday in all of Vietnam and a time when 244
most government offices and businesses are closed. As such, we did not have available to us 245
all possible resources. Nevertheless, despite these challenges, we were able to contain the 246
outbreak in Vinh Phuc and prevent further transmission throughout Vietnam. Our experience 247
may provide useful insights for other communities or countries.
248
In summary, we successfully contained localized transmission of SARS-CoV-2 in a province of 249
approximately one million persons. We learned several lessons in the process. First, the 250
unambiguous direction and concrete guidance from the National Steering Committee on 251
Prevention and Control of COVID-19 was essential. Second, the committee focused its 252
resources on available prevention strategies, namely, rapid detection and isolation of cases 253
and exhaustive contact tracing and immediate quarantine at a variety of levels (health facilities, 254
community facilities, households, entire commune). Third, the committee mobilized all 255
available local resources (human, material, facilities, and finance) to implement these 256
measures. As a result, the district healthcare system, with extremely limited resources, was 257
able to manage the majority of the secondary cases of COVID-19 successfully. Fourth, the 258
committee insisted on multi-sectoral collaboration among health, military, police, and 259
community sectors. The whole-of-government approach taken in Vinh Phuc likely prevented 260
hundreds or thousands of cases in the nearby, densely populated city of Hanoi and, possibly, 261
throughout the rest of Vietnam. From this experience, Vietnam has remained successful in 262
containing COVID-19 with fewer than 300 cases, and no fatalities, after three months of the 263
epidemic.
264
13 Tables and figure:
265
Table 1: Interventions implemented to interrupt transmission of SARS-CoV-2, Vinh Phuc Province, Vietnam, January – March, 266
2020.
267
Intervention Start Date
End Date
Scope
Isolation Jan 26 Feb 13
Initially focused on the National Hospital for Tropical Diseases in Hanoi.
Then expanded to the Quang Ha Polyclinic in Vinh Phuc.
Contact Tracing Jan 26 Mar 2
Began with close contacts of cases, then proceeded with contacts who were not closely associated with the cases.
Quarantine Facility Feb 10 Mar 25
Established at a military school in Vinh Phuc, used for asymptomatic contacts of cases.
Quarantine of Community
Feb 13 Mar 3
Included staffed check points, inspection of materials, establishment of fixed price market, and payments to residents.
House-to-House Checks
Feb 13 Mar 3
Daily temperature and symptom checks and delivery of risk communication messages to all households.
268 269
14 Table 2: Descriptive Epidemiology of Cases of COVID-19, January 17 – February 26, 2020—Vinh Phuc Province, Vietnam.
270
Case Gender Age Travel and contact history Symptoms
Onset date
Hospital, Date of admission
Date of discharge
Clinical outcome
1 Male
29 yrs
Travel from Wuhan on 17 January
Cough 21 Jan
NHTD, 23 Jan
18 Feb Survived
2 Female 24 yrs
Travel from Wuhan on 17 January
Fever, cough, sore throat
25 Jan
NHTD, 26 Jan
10 Feb Survived
3 Female 29 yrs
Travel from Wuhan on 17 January
Fever 26 Jan
NHTD, 2 Feb
10 Feb Survived
4 Male
30 yrs
Travel from Wuhan on 17 January
Fever, cough 27 Jan
NHTD, 30 Jan
10 Feb Survived
5 Female 42 yrs
Visited case 2's home on 22 and 28 January
Fever 31 Jan
QH Pol*
31 Jan
18 Feb Survived
6 Female 29 yrs
Travel from Wuhan on 17 January
Asymptomatic 3 Feb
QH Pol, 5 Feb
20 Feb Survived
15 7 Female
49 yrs
Mother of case 2, same household
Cough 3 Feb
QH Pol, 3 Feb
18 Feb Survived
8 Female 16 yrs
Younger sister of case 2, same household
Asymptomatic 4 Feb
QH Pol, 5 Feb
20 Feb Survived
9 Female 55 yrs
Visited case 2's home on 28 January
Fever, headache 4 Feb
QH Pol, NHTD,
5 Feb
18 Feb Survived
10 Female 3 mos
Stayed with case 2's family from 28-31 January
Cough, runny nose 6 Feb
QH Pol, NPH*, 6 Feb
20 Feb Survived
11 Male
50 yrs
Father of case 2, same household
Fatigue 12 Feb
QH Pol 11 Feb
26 Feb Survived
*National Hospital for Tropical Diseases (NHTD); Quang Ha Polyclinic Hospital (QH Pol); National Pediatric Hospital (NPH) 271
272 273 274 275
16 Table 3. Results of case-finding and contact tracing, Vinh Phuc Province, Vietnam, January-March, 2020
276
Location
Laboratory- confirmed
Cases
Suspected Cases Testing
Negative
Close Contacts
Contacts not considered to be
close Binh Xuyen District
Son Loi Commune 6 40 70 52
All other communes in Binh Xuyen District 3 59 79 148
All other districts 2 48 65 249
All of Vinh Phuc Province 11 147 214 449
277 278
17 Table 4. Impact of Interventions Aimed at Interrupting Transmission of SARS-CoV-2, Vinh Phuc Province, Vietnam, January – 279
March, 2020 280
Case
Days from Onset or First Positive
Test to Admission
Number of Close Contacts
Number of Contacts Not Considered to
be Close
Total Contacts
1 2 3 57 60
2 1 4 47 51
3 7 6 35 41
4 3 4 38 42
5 0 15 8 23
6 2 6 11 17
7 0 4 6 10
8 1 4 44 48
9 1 6 4 10
10 0 2 10 12
11 -1 5 30 35
18 Summary
Measure
Median time onset to admission = 1
day
Total 59 Total 290 Total 349
Median Cases 1-5: 4 contacts
Median Cases 1-5:
38 contacts
Median Cases 1-5:
42 contacts Median Cases
6-11: 4.5 contacts
Median Cases 6-11:
10 contacts
Median Cases 6-10:
10.5 contacts
281
*Case was asymptomatic. Therefore, date of testing is shown instead of date of onset.
282
Figure 1. Map of Binh Xuyen District in Vinh Phuc Province. Bold text indicates names of province, smaller texts indicate 283
commune names. Numbers circled indicate number of COVID-19 cases in the relevant commune. Green triangles indicate 284
quarantine stations. Black camp indicates Provincial Military School of Vinh Phuc. Wheelchair symbol indicates Quang Ha 285
Polyclinic Hospital.
286 287
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