The global influenza hospital surveillance network (GIHSN), a worldwide platform for timely generation of severe influenza epidemiological data

Abstract

Introduction According to World Health Organization (WHO) estimates, annual influenza epidemics are estimated to result in about 3 to 5 million cases of severe illness, and about 290,000 to 650,000 deaths worldwide. While policy makers are expected to place higher value on vaccines indicated for prevention of severe illness, high quality global data on severe influenza are scarce. This is further complicated by the variability of the viruses and the severity of influenza epidemics between years and geographical areas. The Global Influenza Hospital Surveillance Network (GIHSN) supported by the Foundation for Influenza Epidemiology is a platform to generate such important public health data. Methods The GIHSN consists of a network of country sites affiliated with public health authorities coordinating several hospitals. This multicenter, prospective, hospital-based active surveillance, is coordinated by the Open Health Company and funded by the Foundation for Influenza Epidemiology created by Sanofi Pasteur. A standard protocol is shared between sites allowing for comparison and pooling of data across sites. Patients hospitalized during the influenza season are asked for recent (less than 7 days old) influenza-like-illness (ILI) symptoms before admission. All consenting ILI cases are swabbed and tested by multiplex real-time polymerase chain reaction (RT-PCR) for influenza. Influenza positive RT-PCR samples are sub-typed to identify A/H1N1, A/H3N2 strain subtypes or B/Yamagata, B/Victoria lineages. When vaccine uptake allows, vaccine effectiveness is estimated using a test negative design method. Sites are invited to share their data through an online collection tool. Data are then aggregated, and indicators are displayed using state-of-the-art data visualization techniques on the network website www.gihsn.org . Data are managed through an associative engine, which can combine a very large number of data sources and indexes every possible relationship in the data. Users are not restricted to linear exploration within partial views of data and can gain immediate insights and explore data in multiple directions. Results The GIHSN has been progressively scaled up and has generated data for six consecutive seasons, for both Northern and Southern hemisphere, representing now a yearly sample of more than 12,000 individual samples tested by RT-PCR with detailed demographic, clinical and virological data. During the 2016–2017 season, close to 3000 cases of hospitalizations from influenza have been documented. Type of data generated include influenza activity and lengths of epidemics, pattern of strain circulation by subtype by region, burden of severe laboratory confirmed influenza for various populations, analyses of disease risk factors and vaccine effectiveness estimates. Genetic strain sequencing characterization is also generated locally. Results are published yearly in peer reviewed scientific journals and presented in international conferences. For the 2017–2018 season, the GIHSN expanded to more than 40 hospitals in 20 countries. Conclusion The GIHSN platform is a useful tool to fill a knowledge gap about the variability of the influenza burden across season and regions. Other respiratory viruses are now being incorporated. The on-line data collection tool and data display help to provide access to this information in a timely manner to inform public health authorities. Funding statement The GIHSN receive a funding from the Foundation for Influenza Epidemiology and Sanofi Pasteur.