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

Epiwork Logo
Developing the framework for an epidemic forecast infrastructure.

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

7th Framework Logo
Participating countries and volunteers:

The Netherlands 14006
Belgium 4597
Portugal 1897
Italy 4089
Great Britain 8047
Sweden 3559
Germany 171
Austria 380
Switzerland 112
France 6532
Spain 983
Ireland 623
Denmark 738
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.

Hide this information
For archived results click here

Results from Flusurvey 2015/16

This season, 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 flu season. The influenza-like-illness clinical attack rate among active participants (those who completed at least 3 symptoms questionnaire) was 3.3%. Weekly incidence is shown by age group and overall rates.

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. Participants with symptoms did not appear to visit or call health care providers, only 3% visited a healthcare provider (for example GP, hospital and A&E) while 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.

Gender distribution Age group Employment status of respondents

Mode of transport

Most commonly reported flu symptoms

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

2015/16 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 for data collected in wk6 and wk8 since no data was available.

2015/16 Results up to week 20: 

1775 (43.3%) of 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.

This figure above shows the proportion of Flusurvey participants positive for a flu-like illness in the 2015/16 flu season who sought care from a health professional either by calling a service or visiting as well as what medication they may have taken..  red bars represent participants that visited a health professional, blue lines participants who called a healthcare provider and the grey bar are participants who did not seek any healthcare service. It is important to note how the proportion of participants who reported taking painkillers are similar to that of those who did not seek healthcare services.

Previous results from Flusurvey

Last year's Flusurvey reveal that on average, people suffering from a flu-like illness loses the equivalent to two days of healthy life. Although most people recover from flu, it can make people feel very unwell and reduce their quality of life while they are ill. By combining this information with the length of illness reported, Anton Camacho, a Flusurvey researcher at the London School of Hygiene and Tropical Medicine has shown that having flu is equivalent to losing two days of healthy life. The research also established that the amount of healthy life lost to flu increased with age, severity of the symptoms and if the participant was a smoker. This research will be published later this flu season, but to see preliminary data, please see the file below, presented at The Lancet Public Health Conference, November 2013 at the Institute of Child Health 

Icon How Flu affects Quality of Life: Findings from 2013-2014 Flu season (1.9 MB)

Results of last year's Flusurvey

Below you can see what influenced Flusurvey participant's chances of reporting a flu-like illness for the 2013-2014 flu season. Factors in green were protective against flu-like illness.  Factors in red increased the risk. Factors in blue showed no association with reporting a flu-like illness.

Here's how flu rates are looking amongst participants this week (week 10): 

Week 9: Below you can see that reports of flu-like illness have increased in all age groups in the last week. This indicates that we might be seeing the start of a flu like illness across the UK. We'll monitor this closely and check back see whether it increases next week!

Above you can see the weekly incidence reported by Flusurvey.  Last week (week twenty one) reports of flu-like illness remained low in all age groups, although slightly increased from the week before.  It is still looking like we managed to avoid a bad flu season this year!

Will it be a bad flu year?

Last year there was very little flu around.  Here you can track how much flu-like illness our participants are reporting last year (2013/4) compared to the previous year (2012/3).  It looks like there was a very mild season last year.

Where do Flusurvey participants come from?

The figure below shows where Flusurvey participants are based. London, the South, and the East are well represented, but we would like to get a larger proportion from the North, Scotland and Wales.  We'd also like to have more children involved, please tell your friends!

In the twenty first week of last year's flu season, rates of flu-like illness were low.  The highest rates of flu like illness were in the Southwest,  East Midlands, and Scotland. there were almost no cases in Wales. There were few reports from the Northeast so it is difficult to say what is going on there.

Weekly Incidence by age

Weekly incidence of flu-like illness last year (2012-2013 flu season)

This figure shows the pattern of flu-like illness reported by Flusurvey participants in 2012/3. The grey shading shows the school holidays. Over the season you can see the peaks in illness, and the effect that school holidays had on stopping the epidemic. The bottom graph shows % positivity of cases of lab confirmed flu (data provided by the Respiratory DataMart System is a laboratory surveillance tool to monitor influenza and other respiratory viruses based on collated lab results from a network of Public Health England (PHE) and NHS laboratories in England. Respiratory swabs from primary and secondary care are tested for a variety of viruses using real time polymerase chain reaction (RT-PCR) assays. Weekly results are published in the PHE National Influenza Report /)

These results show that there was no increased chance of reporting a flu-like illness in participants who took public transport as compared to participants who did not take public transport.  This finding was the same all across Europe.

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

Manflu - a myth!

The figure below shows the distribution of reported health scores in healthy participants, participants with colds, and participants with influenza-like illness (ILI) last year. Scores reported by men are in blue, by women in pink. It's clear that people with ILI report lower health than people with cold symptoms or no symptoms, but the scores are not noticeably different for men and women. We haven't found any evidence that men are likely to report feeling worse when they're ill; if anything, women seem to report lower health scores.