Abstract
BackgroundYear‐round transmission of influenza has been detected in Vietnam through both national surveillance and other epidemiological studies. Understanding the demographic and clinical features of influenza‐like illness (ILI) presenting to primary care in urban Vietnam is vital to understand these transmission dynamics.MethodsAn observational study of patients with ILI in Ho Chi Minh City, Vietnam, was conducted between August 2013 and November 2015 in a mix of public and private primary care settings. Molecular testing for influenza A and influenza B and 12 other respiratory viruses was performed.ResultsA total of 1152 ILI patients were recruited. 322 and 136 subjects tested positive for influenza A and influenza B, respectively. 193 subjects tested positive for another respiratory virus; most commonly rhinovirus and parainfluenza virus 3. Influenza was detected in 81% of the 116 study weeks. Three peaks of influenza activity were detected; an H3N2 peak April‐June 2014, an influenza B peak July‐December 2014, and a mixed H3N2 and H1N1 peak March‐September 2015. Subjects recruited from private clinics were more likely to have higher income and to have reported previous influenza vaccination. Antibiotic use was common (50.3%) despite limited evidence of bacterial infection.ConclusionInfluenza in southern Vietnam has complex transmission dynamics including periods of intense influenza activity of alternating types and subtypes. Broadening surveillance from hospital to the community in tropical settings is feasible and a valuable for improving our understanding of the global spread and evolution of the virus.
Highlights
Year-round transmission of influenza has been detected in Vietnam through both national surveillance and other epidemiological studies
The objectives of this study were to describe the dynamics and demographic/clinical characteristics of ILI presenting to primary care services within an urban setting in Vietnam over a 27-month period, and to estimate the proportion of ILI caused by influenza A and B
Summary of Design and Conduct of the Observational Study This observational study was conducted between August 2013 and November 2015 at outpatient clinics and community medical practitioners in Ho Chi Minh City (HCMC), Vietnam
Summary
Year-round transmission of influenza has been detected in Vietnam through both national surveillance and other epidemiological studies. Understanding the demographic and clinical features of influenza-like-illness (ILI) presenting to primary care in urban Vietnam is vital to understand these transmission dynamics. Influenza viruses circulate globally and seasonal epidemics are thought to be associated with 3-5 million severe clinical infections and 250,000 to 500,000 deaths each year [1, 2]. Influenza was thought not to be a disease of importance in tropical countries. This has changed considerably in the last ten years [3]. As one of the most populous countries in the tropics, is a potentially globally important site for influenza dynamics, both for its possible contribution to global virus evolution [4, 5] and as a high-risk environment for the emergence of potentially pandemic strains such as highly pathogenic avian influenza subtype H5N1
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