Influenzanet is a system to monitor the activity of influenza-like-illness (ILI) with the aid of volunteers via the internet

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The Seventh Framework Programme (FP7) bundles all research-related EU initiatives.

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Participating countries and volunteers:

The Netherlands 11799
Belgium 3924
Portugal 1720
Italy 4287
Great Britain 4002
Sweden 3559
Germany 179
Austria 482
Switzerland 660
France 6215
Spain 995
Ireland 293
Denmark 1294
InfluenzaNet is a system to monitor the activity of influenza-like-illness (ILI) with the aid of volunteers via the internet. It has been operational in The Netherlands and Belgium (since 2003), Portugal (since 2005) and Italy (since 2008), and the current objective is to implement InfluenzaNet in more European countries.

In 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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Provisional results from 2016/17

The Flusurvey for the 2016/17 season started on the 2nd of November, 2016 with overwhelming support and participation from previous and new participants. The number of participants have been increasing steadily since the season commenced, with an over average response rate (55.0%) for completing the weekly symptoms survey (Figure 1). We are nearly at 4000 registered participants and hope we can keep increasing the numbers as we approach the end of the flu season.
It is important to monitor flu like illness especially among those less likely to seek healthcare services for their symptoms. The overall ILI rate (all age groups) for week 11 was 24.0 per 1,000 (51/2,122 people reported at least 1 ILI), with the 20-44 years age group recording the highest rate of 34.2 per 1,000 (Figure 2)
Figure 1: Number of registered participants compared to those completing the symptoms survey each week up to week 11, 2016/17
Figure 2: FluSurvey ILI incidence by age group, UK - up to week 11, 2016/17

Results from Flusurvey 2015/16

During 2015/16, the Flusurvey recorded additional participants suggesting that the survey is growing in popularity and acceptance. An additional 2500 persons signed up and reported flu like symptoms during the winter season. The cumulative influenza-like-illness clinical attack rate among active participants (those who completed at least 3 symptoms questionnaire) over the period November 2015 to May 2016 was 3.3%. Weekly incidence is shown by age group and overall rates in Figure 7, with the highest rates seen in <20 year olds. These findings are consistent with the PHE influenza surveillance data, which showed that the dominant circulating strain in 2015/16 was influenza A/H1N1pdm09.

On average, people reporting any flu related symptoms lost two and half days from work . And although most people will recover from flu, it can make people feel very unwell and reduce their quality of life while they are ill. Only a small proportion of articipants with acute respiratory symptoms reported visiting or calling health care providers, with only 3% visiting a healthcare provider (for example GP, hospital and A&E) anf 2% called any healthcare service (for example NHSdirect, GP Nurse).

Characteristics of participants

There were 4,104 participants who completed at least one week's symptoms questionaire during the survey, 66.9% of whom were women. The mean age of participants was 42.7 years. A high proportion (67.3%) of respondents can be classified as highly educated and in full employment. The characteristics of participants are summarised below.

Figure 1: Gender distribution of participants, week 40 2015 to week 20 2016
Figure 2: Age Group of participants, 2015-16
Figure 3: Employment status of respondents, 2015-16
Figure 4: Mode of transport of participants, 2015-16

More than half (58.6%) of survey participants reported using their car as a means of transportation compared to public transport (20.8%) or walking (14.3%)

Figure 5: Where do Flusurvey participants come from?

The figure below shows where Flusurvey participants were based. South East and London were very well represented, though we would like to get a larger proportion from Northern Ireland, North East England and Wales.  We'd also like to have more children <17 years of age involved, please tell your friends and family!

Figure 6: Most commonly reported flu symptoms, 2015-16

Above you can see the most commonly reported symptoms amongst cases during the flu season. Sudden onset of symptoms and runny nose were the most frequently reported symptoms while chest pain and fever were least amongst Flusurvey participants.

Figure 7: Weekly ILI rates by age groups in 2015/16, results up to week 20

Data up to week 20 shows that ILI incidence per 1,000 among flusurvey participants peaked at week 8. The highest ILI incidence was observed among 0-19 year olds. 

Note: data for wk 7 is an average of data collected in wk6 and wk8 since no data was available
Figure 8: Weekly ILI incidence per 1000, 2015/16
Figure 9: The reasons respondnents gave for receiving or not receiving the 2015/16 flu vaccine.

1775 (43.3%) participant reported receiving the 2015/16 influenza vaccine. The reason participants gave for receiving or not receiving the flu vaccine are presented in the figure above. Encouragingly, a relatively small proportion of people had negative attitudes about the influenza vaccine (i.e. concerns around safety, side effects or efficacy of vaccine) while increasing vaccine availability and improving convenience of administration (e.g. in the work place) would increase vaccine uptake in the general population.

Figure 10: Healthcare seeking behaviours reported by participants, 2015/16

This figure above shows the proportion of Flusurvey participants reporting a flu-like illness in the 2015/16 flu season and who sought care from a health professional either by calling a service or visiting, or what medication they may have taken. It is important to note how the proportion of participants who reported taking painkillers were similar to that of those who did not seek healthcare services.