National influenza surveillance systems in five European countries: a qualitative comparative framework based on WHO guidance.

BACKGROUND: Influenza surveillance systems vary widely between countries and there is no framework to evaluate national surveillance systems in terms of data generation and dissemination. This study aimed to develop and test a comparative framework for European influenza surveillance. METHODS: Surveillance systems were evaluated qualitatively in five European countries (France, Germany, Italy, Spain, and the United Kingdom) by a panel of influenza experts and researchers from each country. Seven surveillance sub-systems were defined: non-medically attended community surveillance, virological surveillance, community surveillance, outbreak surveillance, primary care surveillance, hospital surveillance, mortality surveillance). These covered a total of 19 comparable outcomes of increasing severity, ranging from non-medically attended cases to deaths, which were evaluated using 5 comparison criteria based on WHO guidance (granularity, timing, representativeness, sampling strategy, communication) to produce a framework to compare the five countries. RESULTS: France and the United Kingdom showed the widest range of surveillance sub-systems, particularly for hospital surveillance, followed by Germany, Spain, and Italy. In all countries, virological, primary care and hospital surveillance were well developed, but non-medically attended events, influenza cases in the community, outbreaks in closed settings and mortality estimates were not consistently reported or published. The framework also allowed the comparison of variations in data granularity, timing, representativeness, sampling strategy, and communication between countries. For data granularity, breakdown per risk condition were available in France and Spain, but not in the United Kingdom, Germany and Italy. For data communication, there were disparities in the timeliness and accessibility of surveillance data. CONCLUSIONS: This new framework can be used to compare influenza surveillance systems qualitatively between countries to allow the identification of structural differences as well as to evaluate adherence to WHO guidance. The framework may be adapted for other infectious respiratory diseases.

Cost-utility analysis of influenza vaccination in a population aged 65 years or older in Spain with a high-dose vaccine versus an adjuvanted vaccine.

BACKGROUND: The normal ageing process is accompanied by immunosenescence and a progressive weakening of the immune system. High-dose inactivated influenza quadrivalent vaccine (HD-QIV) has shown greater immunogenicity, relative efficacy, and effectiveness than the standard-dose inactivated quadrivalent vaccine (SD-QIV). The aim of the study was to assess the cost-utility of an HD-QIV strategy compared with an adjuvanted trivalent inactivated vaccine (aTIV) strategy in the population above 65 years of age in Spain. METHODS: We evaluated the public health and economic benefits of alternatives by using a decision-tree model, which included influenza cases, visits to the general practitioner (GP), visits to the emergency department (ED), hospitalisations, and mortality related to influenza. We performed deterministic and probabilistic sensitivity analyses to account for both epidemiological and economical sources of uncertainty. RESULTS: Our results show that switching from aTIV strategy to HD-QIV would prevent 36,476 cases of influenza, 5,143 visits to GP, 1,054 visits to the ED, 9,193 episodes of hospitalisation due to influenza or pneumonia, and 357 deaths due to influenza - increasing 3,514 life-years and 3,167 quality-adjusted life-years (QALYs). Healthcare costs increase by €78,874,301, leading to an incremental cost-effectiveness ratio (ICER) of €24,353/QALY. The sensitivity analysis indicates that the results are rather robust. CONCLUSION: Our analysis shows that HD-QIV in people over 65 years of age is an influenza-prevention strategy that is at least cost-effective, if not dominant, in Spain. It reduces cases of influenza, GP visits, hospitalisations, deaths, and associated healthcare costs.

Burden of adult varicella hospitalizations in Spain (2001-2007).

A population-based retrospective epidemiological study to estimate the burden of adult varicella hospitalizations in Spain was conducted by using data from the national surveillance system for hospital data, Conjunto Mínimo Básico de Datos (CMBD). Records of all adult patients admitted to the hospital with a diagnosis of varicella (ICD-9-MC codes 052.0-052.9) during a 7-year period (2001-2007) were selected. There were 5,450 hospital discharges with a diagnosis of varicella during the study period. The hospitalization rate for the seven-year study period was 2.2 hospitalizations/100,000 people (CI 95% 2.17-2.29). The highest incidence was observed in the 34-45 year age group [4.10 hospitalizations/100,000 people (CI 95% 3.91-4.28)].There were 149 deaths among hospitalised cases in the study period, which represents a mortality of 0.061 deaths/100,000 people (CI 95% 0.05-0.07) and a case-fatality ratio of 2.73% (CI 95% 2.30-3.17)Adult varicella hospitalizations generate an annual expenditure in Spain of 2,962,912 €. Although varicella is mainly a pediatric disease, it causes an important burden of hospitalization in adults. Hospitalization rates related to varicella infection did not vary during the 7-year study period.