Influenza epidemics and pandemics have a huge impact on society and individuals. The weight and scope of the burden of influenza varies with the age and underlying health of the patient. The disease imposes a significant burden on all individuals, but hospitalization and treatment occur more frequently in high-risk patients (the elderly and those with certain underlying medical conditions); patient populations that are increasing in size. Escalating medical costs have increased the need to quantify the burden of influenza. The first step in any such analysis is to determine the incidence of the disease; with influenza, this is often under-reported, since the illness may be confused with other viral illnesses. In addition to the direct costs of medical care, the indirect costs of influenza are substantial and stem largely from absenteeism and loss of work productivity. Estimates of the cost of influenza in the USA, France and Germany have shown that indirect costs can be five- to 10-fold higher than direct costs. Other intangible costs associated with influenza include impaired performance, which can reduce reaction times, and adverse effects on the quality of life of patients and their families. The costs of interventions should, therefore, be considered in this context. The main approach to the control of influenza and its associated costs is the administration of vaccines. Although vaccines are widely effective, the greatest potential benefits are observed within high-risk groups; vaccination is therefore recommended in many countries for high-risk patients, their carers and healthcare workers. However, the shortcomings of present vaccines, which include manufacturing limitations that prevent guaranteed adequate supply of vaccine, the difficulty in matching vaccines to circulating strains and the need for administration by injection, highlight the need for complementary treatment.