Abstract
In 2003, an internet-based monitoring system of influenza-like illness (ILI), the Great Influenza Survey (GIS), was initiated in Belgium. For the Flemish part of Belgium, we investigate the representativeness of the GIS population and assess the validity of the survey in terms of ILI incidence during eight influenza seasons (from 2003 through 2011). The validity is investigated by comparing estimated ILI incidences from the GIS with recorded incidences from two other monitoring systems, (i) the Belgian Sentinel Network and (ii) the Google Flu Trends, and by performing a risk factor analysis to investigate whether the risks on acquiring ILI in the GIS population are comparable with results in the literature. A random walk model of first order is used to estimate ILI incidence trends based on the GIS. Good to excellent correspondence is observed between the estimated ILI trends in the GIS and the recorded trends in the Sentinel Network and the Google Flu Trends. The results of the risk factor analysis are in line with the literature. In conclusion, the GIS is a useful additional surveillance network for ILI monitoring in Flanders. The advantages are the speed at which information is available and the fact that data is gathered directly in the community at an individual level.
Highlights
For healthcare workers, a timely and accurate system to monitor the spread of seasonal and pandemic influenza in the general population is important
In Belgium, this system is organized by the Scientific Institute of Public Health and is based upon influenza-like illness (ILI) consultations at general practitioners (GPs) that participate in the Belgian Sentinel Network [3]
This result indicates that some volunteers start participating in the Great Influenza Survey (GIS) as a response to their symptoms, but non-regular participation does not lead to higher ILI rates
Summary
A timely and accurate system to monitor the spread of seasonal and pandemic influenza in the general population is important. Because infection with the influenza virus is difficult to diagnose without virological confirmation, the best surveillance indicator of influenza in the community is the incidence of influenza-like illness (ILI). ILI is defined as an illness with symptoms similar to an influenza infection. Traditional surveillance systems rely on clinical and virological information from ILI patients that visit their physician. Due to the ever increasing usage of the internet, internet-based monitoring systems have been set up as well, such as: (i) surveillance based on voluntary participation in an online survey [4,5,6,7], and (ii) surveillance based on ILI-related queries entered at online search engines [8,9,10,11,12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
