This WP is meant to provide a comparative analysis of three systems in Sweden: (1) the existing GP sentinel system of influenza surveillance with the (2) new internet monitoring system (IMS) and (3) a population-based approach (PBA), currently being evaluated on a large-scale pilot study basis.

The self-selection involved in the recruitment of “flu meters” in the IMS system in WP5 raises concerns about possible selection bias that might lead us wrong in future modeling. Therefore, it is desirable to validate the IMS results against a more rigorous population-based epidemiological approach. If deviations are found, we hope that it will be possible to apply correction factors that transform IMS data to “population-based” data. For this purpose, WP6 was conceived to run IMS and PBA in parallel, and to compare their results with each other and also with existing sentinel physician-based influenza surveillance data.

The first year of the project has been dedicated to the development of the Population Based Approach.

During the second year, to compare the three influenza surveillance systems a fully functioning and tested Internet Monitoring System started to be deployed in Sweden in October 2010. The localization, translation, testing and fine tuning activities took place between October 2010 and February 2011. The website can be visited on www.influensakoll.se The website is being tested and a considerable effort on developing a communication plan for the marketing of the IMS system is still ongoing.

Morevoer, during August to September 2010 a new cohort for the population-based approach (PBA) has been established at the Swedish Institute for Infectious Disease Control (Smittskyddsinstitutet – SMI). In total, 2,701 participants were recruited, and they are presently providing continuous incidence data concerning Acute Upper Respiratory Tract Infection (ARI) and Influenza-like Illness (ILI). The continuously updated incidence curve can be found at the page:

http://www.smittskyddsinstitutet.se/publikationer/smis-nyhetsbrev/sjukrapport/sasongen-20102011/