title: Ten-year performance of Influenzanet: ILI time series, risks, vaccine effects, and care-seeking behaviour.
abstract: Recent public health threats have propelled major innovations on infectious disease monitoring, culminating in the development of innovative syndromic surveillance methods. Influenzanet is an internet-based system that monitors influenza-like illness (ILI) in cohorts of self-reporting volunteers in European countries since 2003. We investigate and confirm coherence through the first ten years in comparison with ILI data from the European Influenza Surveillance Network and demonstrate country-specific behaviour of participants with ILI regarding medical care seeking. Using regression analysis, we determine that chronic diseases, being a child, living with children, being female, smoking and pets at home, are all independent predictors of ILI risk, whereas practicing sports and walking or bicycling for locomotion are associated with a small risk reduction. No effect for using public transportation or living alone was found. Furthermore, we determine the vaccine effectiveness for ILI for each season.
authors.affiliation: Instituto Gulbenkian de Ciência, Oeiras, Portugal. Electronic address: vanNoort@gmail.com.
authors.forename: Sander P
authors.initials: SP
authors.lastname: van Noort
authors.affiliation: Instituto Gulbenkian de Ciência, Oeiras, Portugal; Oswaldo Cruz Foundation, Rio de Janeiro, Brazil.
authors.forename: Cláudia T
authors.initials: CT
authors.lastname: Codeço
authors.affiliation: De Grote Griepmeting/Science in Action, Amsterdam, The Netherlands.
authors.forename: Carl E
authors.initials: CE
authors.lastname: Koppeschaar
authors.affiliation: Rega Institute for Medical Research, University of Leuven, Leuven, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: van Ranst
authors.affiliation: ISI Foundation, Turin, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Paolotti
authors.affiliation: Instituto Gulbenkian de Ciência, Oeiras, Portugal.
authors.forename: M Gabriela M
authors.initials: MG
authors.lastname: Gomes
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000818:Animals; D002908:Chronic Disease; D005060:Europe / Q000453:epidemiology; D005260:Female; D015438:Health Behavior; D006801:Humans; D007252:Influenza Vaccines / Q000627:therapeutic use*; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D057805:Pets; D012306:Risk; D012307:Risk Factors; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Influenza-like illness; Risk factors; Syndromic surveillance; Time series; Vaccine effectiveness