Influenzanet is a system to monitor the activity of influenza-like-illness (ILI) with the aid of volunteers via the internet
Developing the framework for an epidemic forecast infrastructure.
http://www.epiwork.eu/
The Seventh Framework Programme (FP7) bundles all research-related EU initiatives.
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4444In contrast with the traditional system of sentinel networks of mainly primary care physicians coordinated by the European Influenza Surveillance Scheme (EISS), InfluenzaNet obtains its data directly from the population. This creates a fast and flexible monitoring system whose uniformity allows for direct comparison of ILI rates between countries.
Any resident of a country where InfluenzaNet is implemented can participate by completing an online application form, which contains various medical, geographic and behavioural questions. Participants are reminded weekly to report any symptoms they have experienced since their last visit. The incidence of ILI is determined on the basis of a uniform case definition.
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Holidays and contact patterns
During 2009, we saw that school holidays had a big impact on the transmission of swine flu. During the holidays, the number of people reporting flu-like symptoms dropped to very low levels.
This could be explained if people with flu decided not to go to their doctors when they were holiday. However, we know from the flusurvey users that this was not the case.
In addition to the weekly symptoms questionnaire, we ask flusurvey users to report their social contacts to help us link social mixing behaviour to risk of infection and to see whether the drop in swine flu cases over the summer could be explained by changes in contact patterns.
Some flusurvey users were especially keen, and recorded their social contacts almost every week. Below are shown how these changes over times for a handful of people (each colour being a different person).
There are clearly differences between people, and the variation makes it hard to see any trends over time. However, when we combine the reports from all users who have completed the contact survey on 12 or more occasions, much clearer patterns emerge:
The red line shows the 'middle' person for each week, while the green and blue lines show where the upper and lower 25% fit in. We can see very clear changes at the end of the summer holiday, during school half term, and during the Christmas holiday period - at these times flusurvey users are away from work so make fewer social contacts.
All this ties in extremely nicely with the epidemic data, and, encouragingly, shows the usefulness of simple contact surveys. We are interested in seeing how patterns will change during a normal flu season, so we'll keep and eye on this in the season to come.