Influenza vaccination uptake and socioeconomic determinants in 11 European countries
Introduction
Influenza is known as a preventable, viral-caused, acute respiratory illness associated with high morbidity and mortality due to its high potential to cause serious complications, especially in the at risk population, i.e., elderly and persons with underlying chronic disease [1].
As a highly contagious infectious disease influenza affects 5–30% of the population worldwide each year [2]. Annually 3–5 million cases of severe infections and 250,000–500,000 deaths worldwide are estimated, added by drop outs at working sites and in reduced productivity. The estimated direct and indirect costs of influenza in industrialized countries sum up to 10–60 million US Dollars per million persons per season [3]. The impact of a median size pandemic could increase the burden of seasonal influenza by a factor of 5–10.
Prophylactic influenza vaccination has been documented over many years to be safe, effective and cost-effective [4], [5], [6]. Annual influenza vaccination is an important means of reducing morbidity and mortality. Therefore it is officially recommended by many European health authorities. While national influenza vaccination recommendations may vary slightly between different countries in Europe, almost all cover the elderly, usually beyond 65 years of age, children and adults with chronic cardiovascular or respiratory diseases, metabolic or renal diseases, as well as healthcare professionals working in close contact to vulnerable patients [7], [8].
Despite accumulated evidence and recommendations, influenza vaccination coverage rates remain clearly suboptimal from a public health perspective [8]. Community-based surveys in five large European countries during the 2001/2002 to 2006/2007 flu seasons revealed vaccination rates between 17.9% and 32.5% in the general population [9]. While the rates were significantly higher for risk groups and compliance was gradually increasing over that period in at least some countries, these rates still reflect many missed opportunities by which people at risk could be prevented from suffering the potential serious complications, by which deaths could be avoided and, finally, by which resources in the health care system and substantial costs could be saved.
In 2006, it was estimated across the 25 countries in the European Union (without Bulgaria and Romania), that nearly 800,000 hospitalizations and nearly 70,000 deaths could be prevented per season if vaccination coverage were to be increased from the existing level of 35.4% up to 100% coverage in the risk groups which may account for up to 49% of the total population [10]. An investment of an additional €1.52 billion for the implementation of a 100% vaccination rate program for all risk groups in the five biggest European countries would result in estimated savings of €39.45 million of reduced primary care visits and further savings of €1.59 billion in reduced hospitalizations, respectively in these countries [10].
Consequently, current research in the field focuses on ways how to improve coverage rates and to elucidate universal drivers and barriers influencing the uptake of influenza vaccination in Europe [8], [9], [11], [12], [13], [14]. Yet, there has been little research done of the effect of socioeconomic factors on the uptake of influenza immunization [15]. Among reported studies the contribution of socioeconomic factors has been discussed not enough differentiated [14] and controversially [16]. However most of those investigations are based on data of subgroups of the population and collected during single seasons making it difficult to gather a picture in terms of macroepidemiology of influenza immunization [7]. In order to obtain comparable data of different countries a uniform method needs to be applied to monitor and assess influenza vaccination uptake.
A database of national survey data systematically and consistently collected over up to seven influenza seasons in samples each representative for the national non-institutionalized population in 11 countries of the European Union, offered the opportunity to assess socioeconomic factors as predictors of influenza immunization with a unique method.
The objective of our study was to explore the contribution of gender, educational level, household income, size of household and population size of living residence as specific socioeconomic factors to the influenza vaccination coverage rates in these 11 European countries.
National campaigns to increase influenza vaccination uptake may need to take a number of driving factors into account, including socioeconomic gradients prevailing in the communities. The effectiveness of policies and interventions may need to be evaluated for specific socioeconomic groups of the population.
Section snippets
Methods
Data collected in scope of annually repeated, cross-sectional, population-based surveys on influenza vaccination uptake performed across 11 European countries were used as source to investigate the research question whether and which socioeconomic factors in which country do have which effect on the probability of being vaccinated against influenza.
Surveys were carried out during seven consecutive influenza seasons (2001/2002 to 2007/2008) in four countries (France, Germany, Italy and UK),
Sample characteristics
The overall sample consisted of 92,101 interviewed persons distributed over 11 European countries with a total population of more than 380 million. Different to the other countries, no persons older than 74 years and both 79 years were included for Spain, Italy and Finland, respectively (Table 1).
Individual vaccination coverage rates across the general population per season and country are summarized in Table 2. As already reported [9] the rates were almost constant with a slight but
Discussion
The aim of this study was to explore whether specific socioeconomic factors contribute to explain the probability of being vaccinated against influenza in 11 European countries by using national survey data representative for the non-institutionalized population aged above 14 years over up to seven consecutive influenza seasons.
The main finding of the present study is that the socioeconomic factors gender, size of household, population size of residence, educational level and household income
Conclusion
Influenza vaccination rates among the assessed European countries are still low and additional efforts are needed to improve immunization against influenza in scope of the worldwide coverage target expressed by the WHO. The results of this analysis may contribute to optimize national influenza vaccination programs and campaigns. It should be a public health goal to reduce health inequalities and to build conditions allowing equitable chances to everyone to benefit from effective preventive
Competing interests
ME was an employee of Novartis Pharma Schweiz AG. PB and TS have been involved in projects on influenza vaccination in Europe funded by the European Vaccine Manufacturers (EVM) Group of the European Federation of Pharmaceutical Industries and Associations (EFPIA), Brussels, Belgium.
Acknowledgements
We thank the GEIG (Groupe d’Expertise et d’Information sur la Grippe) for making the data of France disposable for analysis.
Contributions: ME performed the analyses and wrote the manuscript. PB and TS each reviewed the analyses and the manuscript.
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