Early pandemic influenza (2009 H1N1) in Ho Chi Minh city, Vietnam: A clinical virological and epidemiological analysis

Tran Tinh Hien, Maciej F. Boni, Juliet E. Bryant, Tran Thuy Ngan, Marcel Wolbers, Tran Dang Nguyen, Nguyen Thanh Truong, Nguyen Thi Dung, Do Quang Ha, Vo Minh Hien, Tran Tan Thanh, Le Nguyen Truc Nhu, Le Thi Tam Uyen, Pham Thi Nhien, Nguyen Tran Chinh, Nguyen van Vinh Chau, Jeremy Farrar, H. Rogier van Doorn

Research output: Contribution to journalArticle

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Abstract

Background: To date, little is known about the initial spread and response to the 2009 pandemic of novel influenza A ("2009 H1N1") in tropical countries. Here, we analyse the early progression of the epidemic from 26 May 2009 until the establishment of community transmission in the second half of July 2009 in Ho Chi Minh City (HCMC), Vietnam. In addition, we present detailed systematic viral clearance data on 292 isolated and treated patients and the first three cases of selection of resistant virus during treatment in Vietnam. Methods and Findings: Data sources included all available health reports from the Ministry of Health and relevant health authorities as well as clinical and laboratory data from the first confirmed cases isolated at the Hospital for Tropical Diseases in HCMC. Extensive reverse transcription (RT)-PCR diagnostics on serial samples, viral culture, neuraminidase-inhibition testing, and sequencing were performed on a subset of 2009 H1N1 confirmed cases. Virological (PCR status, shedding) and epidemiological (incidence, isolation, discharge) data were combined to reconstruct the initial outbreak and the establishment of community transmission. From 27 April to 24 July 2009, approximately 760,000 passengers who entered HCMC on international flights were screened at the airport by a body temperature scan and symptom questionnaire. Approximately 0.15% of incoming passengers were intercepted, 200 of whom tested positive for 2009 H1N1 by RT-PCR. An additional 121 out of 169 nontravelers tested positive after self-reporting or contact tracing. These 321 patients spent 79% of their PCR-positive days in isolation; 60% of PCR-positive days were spent treated and in isolation. Influenza-like illness was noted in 61% of patients and no patients experienced pneumonia or severe outcomes. Viral clearance times were similar among patient groups with differing time intervals from illness onset to treatment, with estimated median clearance times between 2.6 and 2.8 d post-treatment for illness-to-treatment intervals of 1-4 d, and 2.0 d (95% confidence interval 1.5-2.5) when treatment was started on the first day of illness. Conclusions: The patients described here represent a cross-section of infected individuals that were identified by temperature screening and symptom questionnaires at the airport, as well as mildly symptomatic to moderately ill patients who self-reported to hospitals. Data are observational and, although they are suggestive, it is not possible to be certain whether the containment efforts delayed community transmission in Vietnam. Viral clearance data assessed by RT-PCR showed a rapid therapeutic response to oseltamivir.

Original languageEnglish (US)
JournalPLoS medicine
Volume7
Issue number5
DOIs
StatePublished - May 2010

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Vietnam
Pandemics
Human Influenza
Polymerase Chain Reaction
Airports
Reverse Transcription
Health
Therapeutics
Contact Tracing
Oseltamivir
Sick Leave
Information Storage and Retrieval
Neuraminidase
Body Temperature
Disease Outbreaks
Pneumonia
Confidence Intervals
Viruses
Temperature
Incidence

All Science Journal Classification (ASJC) codes

  • Medicine(all)

Cite this

Hien, Tran Tinh ; Boni, Maciej F. ; Bryant, Juliet E. ; Ngan, Tran Thuy ; Wolbers, Marcel ; Nguyen, Tran Dang ; Truong, Nguyen Thanh ; Dung, Nguyen Thi ; Ha, Do Quang ; Hien, Vo Minh ; Thanh, Tran Tan ; Nhu, Le Nguyen Truc ; Uyen, Le Thi Tam ; Nhien, Pham Thi ; Chinh, Nguyen Tran ; Chau, Nguyen van Vinh ; Farrar, Jeremy ; van Doorn, H. Rogier. / Early pandemic influenza (2009 H1N1) in Ho Chi Minh city, Vietnam : A clinical virological and epidemiological analysis. In: PLoS medicine. 2010 ; Vol. 7, No. 5.
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author = "Hien, {Tran Tinh} and Boni, {Maciej F.} and Bryant, {Juliet E.} and Ngan, {Tran Thuy} and Marcel Wolbers and Nguyen, {Tran Dang} and Truong, {Nguyen Thanh} and Dung, {Nguyen Thi} and Ha, {Do Quang} and Hien, {Vo Minh} and Thanh, {Tran Tan} and Nhu, {Le Nguyen Truc} and Uyen, {Le Thi Tam} and Nhien, {Pham Thi} and Chinh, {Nguyen Tran} and Chau, {Nguyen van Vinh} and Jeremy Farrar and {van Doorn}, {H. Rogier}",
year = "2010",
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Hien, TT, Boni, MF, Bryant, JE, Ngan, TT, Wolbers, M, Nguyen, TD, Truong, NT, Dung, NT, Ha, DQ, Hien, VM, Thanh, TT, Nhu, LNT, Uyen, LTT, Nhien, PT, Chinh, NT, Chau, NVV, Farrar, J & van Doorn, HR 2010, 'Early pandemic influenza (2009 H1N1) in Ho Chi Minh city, Vietnam: A clinical virological and epidemiological analysis', PLoS medicine, vol. 7, no. 5. https://doi.org/10.1371/journal.pmed.1000277

Early pandemic influenza (2009 H1N1) in Ho Chi Minh city, Vietnam : A clinical virological and epidemiological analysis. / Hien, Tran Tinh; Boni, Maciej F.; Bryant, Juliet E.; Ngan, Tran Thuy; Wolbers, Marcel; Nguyen, Tran Dang; Truong, Nguyen Thanh; Dung, Nguyen Thi; Ha, Do Quang; Hien, Vo Minh; Thanh, Tran Tan; Nhu, Le Nguyen Truc; Uyen, Le Thi Tam; Nhien, Pham Thi; Chinh, Nguyen Tran; Chau, Nguyen van Vinh; Farrar, Jeremy; van Doorn, H. Rogier.

In: PLoS medicine, Vol. 7, No. 5, 05.2010.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Early pandemic influenza (2009 H1N1) in Ho Chi Minh city, Vietnam

T2 - A clinical virological and epidemiological analysis

AU - Hien, Tran Tinh

AU - Boni, Maciej F.

AU - Bryant, Juliet E.

AU - Ngan, Tran Thuy

AU - Wolbers, Marcel

AU - Nguyen, Tran Dang

AU - Truong, Nguyen Thanh

AU - Dung, Nguyen Thi

AU - Ha, Do Quang

AU - Hien, Vo Minh

AU - Thanh, Tran Tan

AU - Nhu, Le Nguyen Truc

AU - Uyen, Le Thi Tam

AU - Nhien, Pham Thi

AU - Chinh, Nguyen Tran

AU - Chau, Nguyen van Vinh

AU - Farrar, Jeremy

AU - van Doorn, H. Rogier

PY - 2010/5

Y1 - 2010/5

N2 - Background: To date, little is known about the initial spread and response to the 2009 pandemic of novel influenza A ("2009 H1N1") in tropical countries. Here, we analyse the early progression of the epidemic from 26 May 2009 until the establishment of community transmission in the second half of July 2009 in Ho Chi Minh City (HCMC), Vietnam. In addition, we present detailed systematic viral clearance data on 292 isolated and treated patients and the first three cases of selection of resistant virus during treatment in Vietnam. Methods and Findings: Data sources included all available health reports from the Ministry of Health and relevant health authorities as well as clinical and laboratory data from the first confirmed cases isolated at the Hospital for Tropical Diseases in HCMC. Extensive reverse transcription (RT)-PCR diagnostics on serial samples, viral culture, neuraminidase-inhibition testing, and sequencing were performed on a subset of 2009 H1N1 confirmed cases. Virological (PCR status, shedding) and epidemiological (incidence, isolation, discharge) data were combined to reconstruct the initial outbreak and the establishment of community transmission. From 27 April to 24 July 2009, approximately 760,000 passengers who entered HCMC on international flights were screened at the airport by a body temperature scan and symptom questionnaire. Approximately 0.15% of incoming passengers were intercepted, 200 of whom tested positive for 2009 H1N1 by RT-PCR. An additional 121 out of 169 nontravelers tested positive after self-reporting or contact tracing. These 321 patients spent 79% of their PCR-positive days in isolation; 60% of PCR-positive days were spent treated and in isolation. Influenza-like illness was noted in 61% of patients and no patients experienced pneumonia or severe outcomes. Viral clearance times were similar among patient groups with differing time intervals from illness onset to treatment, with estimated median clearance times between 2.6 and 2.8 d post-treatment for illness-to-treatment intervals of 1-4 d, and 2.0 d (95% confidence interval 1.5-2.5) when treatment was started on the first day of illness. Conclusions: The patients described here represent a cross-section of infected individuals that were identified by temperature screening and symptom questionnaires at the airport, as well as mildly symptomatic to moderately ill patients who self-reported to hospitals. Data are observational and, although they are suggestive, it is not possible to be certain whether the containment efforts delayed community transmission in Vietnam. Viral clearance data assessed by RT-PCR showed a rapid therapeutic response to oseltamivir.

AB - Background: To date, little is known about the initial spread and response to the 2009 pandemic of novel influenza A ("2009 H1N1") in tropical countries. Here, we analyse the early progression of the epidemic from 26 May 2009 until the establishment of community transmission in the second half of July 2009 in Ho Chi Minh City (HCMC), Vietnam. In addition, we present detailed systematic viral clearance data on 292 isolated and treated patients and the first three cases of selection of resistant virus during treatment in Vietnam. Methods and Findings: Data sources included all available health reports from the Ministry of Health and relevant health authorities as well as clinical and laboratory data from the first confirmed cases isolated at the Hospital for Tropical Diseases in HCMC. Extensive reverse transcription (RT)-PCR diagnostics on serial samples, viral culture, neuraminidase-inhibition testing, and sequencing were performed on a subset of 2009 H1N1 confirmed cases. Virological (PCR status, shedding) and epidemiological (incidence, isolation, discharge) data were combined to reconstruct the initial outbreak and the establishment of community transmission. From 27 April to 24 July 2009, approximately 760,000 passengers who entered HCMC on international flights were screened at the airport by a body temperature scan and symptom questionnaire. Approximately 0.15% of incoming passengers were intercepted, 200 of whom tested positive for 2009 H1N1 by RT-PCR. An additional 121 out of 169 nontravelers tested positive after self-reporting or contact tracing. These 321 patients spent 79% of their PCR-positive days in isolation; 60% of PCR-positive days were spent treated and in isolation. Influenza-like illness was noted in 61% of patients and no patients experienced pneumonia or severe outcomes. Viral clearance times were similar among patient groups with differing time intervals from illness onset to treatment, with estimated median clearance times between 2.6 and 2.8 d post-treatment for illness-to-treatment intervals of 1-4 d, and 2.0 d (95% confidence interval 1.5-2.5) when treatment was started on the first day of illness. Conclusions: The patients described here represent a cross-section of infected individuals that were identified by temperature screening and symptom questionnaires at the airport, as well as mildly symptomatic to moderately ill patients who self-reported to hospitals. Data are observational and, although they are suggestive, it is not possible to be certain whether the containment efforts delayed community transmission in Vietnam. Viral clearance data assessed by RT-PCR showed a rapid therapeutic response to oseltamivir.

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