The Global Influenza Hospital Surveillance Network (GIHSN)

A New Platform to Describe the Epidemiology of Severe Influenza

Joan Puig-Barberà; Anita Tormos; Svetlana Trushakova; Anna Sominina; Maria Pisareva; Meral A. Ciblak; SelimBadur; Hongjie Yu; Benjamin J. Cowling; Elena Burtseva


Influenza Resp Viruses. 2015;9(6):277-286. 

In This Article

Abstract and Introduction


Background Influenza is a global public health problem. However, severe influenza only recently has been addressed in routine surveillance.

Objectives The Global Influenza Hospital Surveillance Network (GIHSN) was established to study the epidemiology of severe influenza in consecutive seasons in different countries. Our objective is to describe the GIHSN approach and methods.

Methods The GIHSN uses prospective active surveillance to identify consecutive influenza admissions in permanent residents of well-defined geographic areas in sites around the world. A core common protocol is followed. After consent, data are collected on patient characteristics and clinical outcomes, respiratory swabs are obtained, and the presence of influenza virus and subtype or lineage is ascertained by polymerase chain reaction. Data are collated and analyzed at the GIHSN coordination center.

Results The GIHSN has run its activities for two consecutive influenza seasons, 2012–2013 and 2013–2014, and hospitals in Brazil, China, France, Russian Federation, Turkey, and Spain have been involved in one or both seasons. Consistency on the application of the protocol and heterogeneity for the first season have been addressed in two previous publications. During both seasons, 19 677 eligible admissions were recorded; 11 843 (60%) were included and tested, and 2713 (23%) were positive for influenza: 991 (37%) A(H1N1); 807 (30%) A(H3N2); 583 (21%) B/Yamagata; 56 (2%) B/Victoria and 151 (6%) influenza A; and 125 (5%) influenza B were not characterized.

Conclusions The GIHSN is a platform that provides information on severe influenza worldwide, applying a common core protocol and a consistent case definition.


Influenza infection results in significant morbidity and mortality. Influenza is believed to infect 10–20% of the population annually; 5–10% of adults and 20–30% of children will show some clinical manifestation and resulting in about 3–5 million cases of severe illness, and about 250 000–500 000 deaths.[1–4] Influenza illness can result in hospitalization and death mainly among high-risk groups, but also in a substantial proportion of previously healthy subjects.[5]

Groups at particular risk of severe influenza include pregnant women, children aged <5 years, the elderly, and individuals with underlying health conditions such as HIV/AIDS, asthma, obesity, and chronic heart or lung diseases.[6] Less is known about the impact of severe influenza in previously healthy subjects. Severe disease due to influenza only recently has been addressed in routine surveillance systems.[7] The level of evidence to support risk factors for influenza-related complications is limited or absent, and some well-accepted risk factors, including pregnancy, are discussed.[8] Prospective hospital-based studies with laboratory-confirmed endpoints are required to better assess the contribution of influenza to severe morbidity.[9]

Historically, influenza surveillance has focused on virological monitoring and collection of specimens to support vaccine strain selection. In recent years, especially after the 2009 pandemic season, influenza surveillance has been expanded as recommended by the World Health Organization (WHO) to include more epidemiological information to complement the virological data.[10]

Various existing networks monitor hospitalizations associated with laboratory-confirmed influenza. Some focus on the description of influenza circulation at a country level, such as Southern Hemisphere Influenza Vaccine Effectiveness Research and Surveillance (SHIVERS),[7] sentinel hospitals in Australia,[11] and the Influenza Hospitalization Network (FluSurv-NET) and the New Vaccine Surveillance Network (NVSN) in the United States,[12] whereas others have a broader focus such as the Red para la Evaluación de la Efectividad de la Vacuna en Latino América y el Caribe – influenza (REVELAC-i) in Latin America,[13] InHove in Europe,[14] and more globally, International Network for Strategic Initiatives in Global HIV Trials (INSIGHT).[15] Some networks seek to capture information generated as part of routine patient care and rely on a retrospective case-ascertainment approach; others perform active surveillance, applying different sampling strategies to enroll hospitalized patients in whom respiratory specimens are obtained independently of clinician ordering. Differences in the sources of information, case ascertainment, definitions of criteria for inclusion, and geographic span have an impact on the magnitude of disease burden estimates and of the relatedness of various risk factors with influenza.[16] This makes it difficult to compare the influenza burden between countries and provide a global estimate of disease burden.[12]

Understanding the population burden of influenza, and the risk factors for influenza virus infection and influenza-associated severe disease, requires adequately powered studies that collect epidemiological and clinical data from laboratory-confirmed cases during various seasons, and using a consistent approach. The Global Influenza Hospital Surveillance Network (GIHSN), using a standardized protocol based on a prospective and common approach to case selection for testing and data collection, may fill this gap.

The GIHSN is a public–private partnership between Sanofi Pasteur, Lyon, France; Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), Valencia, Spain; Fondation Mérieux, Lyon, France; D.I. Ivanovsky Institute of Virology, Moscow, Russian Federation; Research Institute of Influenza, St. Petersburg, Russian Federation; National Influenza Reference Laboratory Capa-Istanbul, Istanbul, Turkey; Key Laboratory of Surveillance and Early-warning on Infectious Disease, Division of Infectious Disease, Chinese Center for Disease Control and Prevention, Beijing, China; and Li Ka Shing Faculty of Medicine, School of Public Health, The University of Hong Kong, Hong Kong, China. All of these institutions act as coordinating sites. Each coordinating site supervises a local network of hospitals in its country or geographic region and follows the GIHSN core reference protocol; FISABIO acts as the GIHSN coordinating center.

The main goals of the GIHSN are to describe circulating virus types and subtypes, and their relationship to global and regional patterns of severe disease; develop an understanding of the relationship of virus strains to severe disease, determine influenza-related burden of severe disease; and estimate how much severe disease is prevented by influenza vaccination.[5,17]

Here, we describe in detail the GIHSN approach and methods to attain these goals.