The burden of seasonal influenza-associated complications in Italy: a systematic review

Abstract

Abstract Background Influenza is the infectious disease with the highest impact on population health in the European Union in terms of disability-adjusted life years. Reliable country-specific influenza-associated burden estimates play a crucial role in informing prevention and control measures to minimize the health and economic burden of the disease. Our purpose was to provide a comprehensive summary of available scientific literature on the burden of seasonal influenza on the Italian population. Methods We performed a systematic literature review of articles published until 31 July 2020. PubMed, Embase and Web of Science were searched. The search strategy included a combination of search terms related to burden, influenza and Italian population. We included studies investigating seasonal influenza-related complications and/or mortality in Italy. A meta-analysis of data was not pre-planned because of the expected heterogeneity in study populations and outcomes. Results A total of 16 studies were included in the qualitative synthesis, out of an original yield of 9,268 articles. Ten (62.5%) and 8 (50%) studies analyzed influenza-related complications and hospitalizations, respectively, while 8 (50%) assessed influenza-related deaths. Only 3 studies (19.7%) concerned pediatric age. The synthesis of results showed that patients with chronic conditions might have an increased risk for complications up to almost 3 times as compared to healthy people. Hospitalization due to influenza can occur from less than 1% to more than 5% according to the study setting (general practice or emergency room). Excess deaths rates were estimated to be over 6-fold higher for the elderly than for the rest of population. Conclusions Although there are still gaps in existing data, there is evidence of the significant burden that influenza places each year especially on high-risk groups. Summaries of the available data may inform decision-making in regard to vaccine strategies and public health policies. Key messages Existing data show evidence of significant burden of influenza on Italian population, especially on high-risk groups. Summaries of country-specific influenza-related burden are crucial in informing vaccine strategies.