PIN17 - Global Burden of Seasonal Influenza Disease: A Structured Literature Review

Abstract

To review published data on the global burden of seasonal influenza in terms of epidemiology, economics, and impact on health-related quality of life (HRQoL). The overall incidence of seasonal influenza was estimated from the incidence rates of infected cases in the placebo groups of clinical trials on vaccines and prophylactic antivirals identified in systematic literature reviews. Targeted searches were performed on Medline to assess: the overall economic burden of influenza from observational studies, HRQoL associated with influenza and excess mortality/hospitalization rates during influenza outbreaks based on statistical regression analyses. Geographical scope covered the US, EU5 and Japan. Average incidence of laboratory-confirmed influenza was estimated between 3.71% in adults and 35.39% in children over 6 and up to 16 years old (yo). Large variability, related to different factors including season, country and target population, was observed between studies. The incidence rate of hospitalization appeared relatively high in <5 yo children, declined in 5-17 yo children and increased progressively after 18 yo. Patients aged >65 yo had the highest mortality rates. Type A influenza caused more hospitalizations and deaths than type B. Influenza resulted in a significant economic burden, including office visits, laboratory tests, emergency department visits, hospital stays with possible ICU admission, and medications. Major cost components were the productivity costs (absenteeism of infected adults or parents of infected children), the physician visit costs and the hospitalization costs related to influenza or its complications. Although the HRQoL impact of influenza on the infected population is often highlighted in evaluations of influenza vaccines and treatments, data on the HRQoL impact of influenza are scarce. Despite efforts to vaccinate high-risk individuals, influenza remains associated with a substantial public health and economic burden in developed countries, mostly related to complications in high-risk patients, and absenteeism in otherwise healthy patients.