Besides the suffering of individual patients caused by seasonal influenza, which also has an impact on society as a whole, several other negative effects on society and its functioning may take place. Adults missing working days due to influenza represent a considerable proportion of the burden of influenza. In addition, children and elderly patients may need additional care, which may also impact on family and/or friends. Owing to the rapid onset of influenza symptoms, there is little time for patients to plan for days or weeks out of action from work, school or other day-to-day activities. This may result in suboptimal functioning or even disruption of usual services, like those provided by hospitals, other healthcare facilities, banks, stores, government offices and post offices.