Early Pandemic Influenza (2009 H1N1) in Ho Chi Minh City, Vietnam: A Clinical Virological and Epidemiological Analysis

Hien, Tran Tinh; Bryant, Juliet E.; Ngan, Tran Thuy; Wolbers, Marcel; Nguyen, Tran Dang; Truong, Nguyen Thanh; Dung, Nguyễn Thị; Ha, Do Quang; Hien, Vo Minh; Thanh, Tran Tan; Nhu, Le Nguyen Truc; Uyen, Le Thi Tam; Nhien, Pham Thi; Chinh, Nguyen Tran; Châu, Nguyễn Văn Vĩnh; Farrar, Jeremy; Doorn, H. Rogier van

doi:10.1371/journal.pmed.1000277

Cited by 53 publications

(38 citation statements)

References 33 publications

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“…The lack of significant differences in the persistence of PCR positivity in treated vs. untreated patients is in agreement with data from other studies carried out on seasonal influenza strains [27], and in apparent contrast with other studies, showing a significant shortening of the duration of viral shedding in A/H1N1pdm -patients exposed to NAI [28,10]. In another study conducted only in treated patients, more prolonged viral shedding was observed in subjects < 13 years of age than in older patients [15].…”

Section: Discussionsupporting

confidence: 92%

Duration of viral shedding in hospitalized patients infected with pandemic H1N1

et al. 2011

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BackgroundThe first influenza pandemic of the 21th century was ignited by a new strain of influenza A virus (A/H1N1pdm). Specific patient groups, including those with comorbidities, pregnant women, young children, older and immunocompromised patients, are at increased risk for serious influenza-related disease. This study was aimed at investigating the influence of clinical presentation, antiviral treatment and possible drug resistance-associated mutations, on the extent and duration of viral shedding in patients infected with A/H1N1pdm.MethodsAn observational study was performed, based on retrospective review of clinical and laboratory records of patients who were hospitalized for A/H1N1pdm infection at the National Institute for Infectious Diseases "L. Spallanzani", Rome, Italy, between April 24 and December 31, 2009. Among 119 hospitalized patients, 39 were selected for a post hoc analysis, based on the availability of serial nasopharyngeal swabs samples and related information.ResultsEleven out of the 39 study patients (28.2%) presented with pneumonia; 29 (74.4%) received antiviral treatment. Patients with pneumonia were significantly older than patients without pneumonia. The mean values of viral RNA concentration were not significantly increased in patients with pneumonia, but a significant increase in the duration of viral shedding was observed as compared to patients without pneumonia. In patients receiving antivirals, the viral RNA concentration was significantly reduced in comparison to untreated patients at days 4-5 after symptom onset, while the overall duration of viral shedding was only marginally affected. A significant correlation between duration of viral shedding and time elapsed between symptom onset and therapy start was observed, with a significant reduction of days of viral shedding when therapy was initiated within 2 days of symptoms appearance. No known drug resistance mutations were detected in patients with prolonged viral shedding.ConclusionsOur results show that severe respiratory illness is associated with delayed virus clearance in patients with A/H1N1pdm infection. Antivirals caused an early reduction of viral load, but only marginally affected the overall duration of shedding. Prolonged shedding was not associated with the emergence of strains carrying known drug-resistance mutations.

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Section: Discussionsupporting

confidence: 92%

Duration of viral shedding in hospitalized patients infected with pandemic H1N1

et al. 2011

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“…There was little difference in the ranges of mean viral shedding duration between the adults (3–8 days) and children (4–8 days) with similar observations for the respective median values (Figure ). Comparison of viral shedding duration measured by PCR between community‐based child and adult cases was made directly in five studies; children had longer shedding duration in three of the studies, two by a mean of 1·2 days (of which P < 0·01 for one of the studies) and the other by 0·4 day but was longer in adults in the other studies by 0·4 and 1·0 days . An additional paper that compared shedding duration in community‐based cases but measured by viral culture found a mean of 5·7 days in children compared with 3·7 days in adults ( P = 0·03) …”

Section: Resultsmentioning

confidence: 99%

Systematic review of influenza A(H1N1)pdm09 virus shedding: duration is affected by severity, but not age

Fielding

Kelly

Mercer

et al. 2013

Influenza Resp Viruses

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Duration of viral shedding following infection is an important determinant of disease transmission, informing both control policies and disease modelling. We undertook a systematic literature review of the duration of influenza A(H1N1)pdm09 virus shedding to examine the effects of age, severity of illness and receipt of antiviral treatment. Studies were identified by searching the PubMed database using the keywords ‘H1N1’, ‘pandemic’, ‘pandemics’, ‘shed’ and ‘shedding’. Any study of humans with an outcome measure of viral shedding was eligible for inclusion in the review. Comparisons by age, degree of severity and antiviral treatment were made with forest plots. The search returned 214 articles of which 22 were eligible for the review. Significant statistical heterogeneity between studies precluded meta-analysis. The mean duration of viral shedding generally increased with severity of clinical presentation, but we found no evidence of longer shedding duration of influenza A(H1N1)pdm09 among children compared with adults. Shorter viral shedding duration was observed when oseltamivir treatment was administered within 48 hours of illness onset. Considerable differences in the design and analysis of viral shedding studies limit their comparison and highlight the need for a standardised approach. These insights have implications not only for pandemic planning, but also for informing responses and study of seasonal influenza now that the A(H1N1)pdm09 virus has become established as the seasonal H1N1 influenza virus.

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“…In contrast to the original reports of severe and fatal disease, prospective studies demonstrated seroconversion in asymptomatic or only mildly asymptomatic individuals [14,15]. Many risk factors for severe pH1N1 influenza were identified that are similar to the risk factors for severe seasonal influenza.…”

Section: Introductionmentioning

confidence: 88%

Patients Hospitalized with pH1N1 Influenza in an Academic Community Medical Center

Bergman

Livornese²,

Sambhara³

et al. 2011

TORMJ

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Background:The emergence of a novel strain of pandemic influenza (pH1N1) in 2009 presented significant challenges to health care facilities worldwide. In our academic community medical center in suburban Philadelphia, we noted our first pH1N1 diagnosis in September 2009. We sought to assess the impact of pH1N1 disease on our hospitalized patient population.Methods:We prospectively collected clinical and epidemiological data on 29 consecutive patients that were admitted to our hospital with a primary or secondary diagnosis of influenza from October 1-November 30, 2009. Data were obtained through care of the patients and chart review.Results:Prominent symptoms on admission included fever, hypoxia, cough, myalgias, and diarrhea, with leukocytosis and neutrophilia. Pre-existing medical conditions included asthma, pregnancy, immunosuppressive therapy, and sickle cell disease. All but 5 of the patients were under 60 years of age. Three patients had culture-documented bacterial or mycoplasma infections. All but two of the patients received oseltamivir. Six required admission to the intensive care unit but only one patient died.Conclusions:Our population of hospitalized patients with novel pH1N1 influenza demonstrated many of the features that have been associated with pH1N1 disease in other populations. Most of the patients were women and none of the patients died directly as a complication of influenza. We observed a cluster of patients with a tetrad of features comprising a history of asthma, obesity, female gender, and African-American race. Individuals with this constellation of factors should be specifically targeted for pH1N1 vaccination.

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Early Pandemic Influenza (2009 H1N1) in Ho Chi Minh City, Vietnam: A Clinical Virological and Epidemiological Analysis

Abstract: Rogier van Doorn and colleagues analyze the initial outbreak, attempts at containment, and establishment of community transmission of pandemic H1N1 influenza in Ho Chi Minh City, Vietnam.

Cited by 53 publications

References 33 publications

Duration of viral shedding in hospitalized patients infected with pandemic H1N1

Duration of viral shedding in hospitalized patients infected with pandemic H1N1

Systematic review of influenza A(H1N1)pdm09 virus shedding: duration is affected by severity, but not age

Patients Hospitalized with pH1N1 Influenza in an Academic Community Medical Center

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