OPEN ACCESS: All research articles are freely available online, with no word limit. Find out more about the BMJ's open access policy. Submit your paper.
Objective To describe the clinical features and effectiveness of oseltamivir on disease progression and viral RNA shedding in patients with mild pandemic 2009 influenza A(H1N1) virus infection.
Design Opportunistic retrospective review of medical charts of patients with confirmed 2009 H1N1 identified through the national surveillance system in China from May to July 2009.
Setting Under coordination of the Ministry of Health, local health departments were asked to collect medical records of confirmed patients and send them to the Chinese Centre for Disease Control and Prevention on a voluntary basis as part of the public health response.
Population 1291 patients with confirmed 2009 H1N1 infection and available data for chart review.
Main outcome measures Demographic characteristics, comorbidities, symptoms and signs, laboratory tests, findings on chest radiography, antiviral treatment, duration of fever, and duration of viral RNA shedding.
Results The median age of 1291 patients was 20 years (interquartile range 12-26); 701 (54%) were male. The most common symptoms were fever (820, 64%), cough (864, 67%), sore throat (425, 33%), sputum (239, 19%), and rhinorrhoea (228, 18%). Of 920 patients who underwent chest radiography, 110 (12%) had abnormal findings consistent with pneumonia. Some 983 (76%) patients were treated with oseltamivir from a median of the third day of symptoms (2-4). No patients required admission to the intensive care unit or mechanical ventilation. 2009 H1N1 was shed from one day before onset of symptoms to up to eight days after onset in most (91%) patients, with a median of 5 (3-6) days of shedding after onset. Treatment with oseltamivir significantly protected against subsequent development of radiographically confirmed pneumonia (odds ratio 0.12, 95% confidence interval 0.08 to 0.18), and treatment started within two days of symptom onset reduced the duration of fever and viral RNA shedding.
Conclusions Chinese patients with 2009 H1N1 infection predominantly presented with features of uncomplicated, self limiting acute respiratory illness. 2009 H1N1 might be shed longer than seasonal influenza virus. Treatment with oseltamivir was associated with a significantly reduced development of radiographically confirmed pneumonia and a shorter duration of fever and viral RNA shedding. Though these patients benefited from treatment, the findings should be interpreted with caution as the study was retrospective and not all patients underwent chest radiography.
We thank the all designated hospitals and local Centres for Disease Control and Prevention for assistance in coordinating data collection, and the Ministry of Health in China for generously facilitating this study.
Contributors: HY and WY conceived, designed, and supervised the study, finalised the analysis, and interpreted the findings. QL, YY, LZ, NX, YH, XG, and YZ assisted in data collection and analysis. HY wrote the drafts of the manuscript. HRvanD and JF interpreted the findings and commented on and helped revise drafts of the manuscript. All other coauthors (ZG, ZF, YW) participated in collection and management of data. HY is guarantor.
Funding: This study was supported by grants from US National Institutes of Health (Comprehensive International Program for Research on AIDS grant U19 AI51915), the China-US Collaborative Program on Emerging and Re-emerging Infectious Diseases, South East Asia Infectious Disease Clinical Research Network, and Wellcome Trust Major Overseas Programme, Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. None of the funders had any role in the study design and the collection, analysis, and interpretation of data, or in the writing of the article and the decision to submit it for publication. The researchers confirm their independence from funders and sponsors. All authors had full access to all data included in the study and are jointly responsible for the integrity of the data and accuracy of data analyses.
Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare: no support from any institution for the submitted work; no financial relationships with any institutions that might have an interest in the submitted work in the previous 3 years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: This study was considered to be part of a continuing public health outbreak investigation by the Ministry of Health of China and exempt from institutional review board assessment. All data were kept confidential without patient identifiers.
Data sharing: Technical appendix, statistical code, and dataset are available from the corresponding author at yuhj@chinacdc.cn for re-analysis.
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.
Open access
Social bookmarking