Impact of flu on hospital admissions during 4 flu seasons in Spain, 2000-2004

Influenza hospitalisations in Spain between the last influenza and COVID-19 pandemic (2009-2019)

Knowing the burden of severe disease caused by influenza is essential for disease risk communication, to understand the true impact of vaccination programmes and to guide public health and disease control measures. We estimated the number of influenza-attributable hospitalisations in Spain during the 2010-2011 to 2019-2020 seasons - based on the hospitalisations due to severe acute respiratory infection (SARI) in Spain using the hospital discharge database and virological influenza information from the Spanish Influenza Sentinel Surveillance System (SISSS). The weekly numbers of influenza-attributable hospitalisations were calculated by multiplying the weekly SARI hospitalisations by the weekly influenza virus positivity, obtained from the SISSS in each season, stratified by age group and sex. The influenza-related hospitalisation burden is age-specific and varies significantly by influenza season. People aged 65 and over yielded the highest average influenza-attributable hospitalisation rates per season (615.6 per 100,000), followed by children aged under 5 (251.2 per 100,000). These results provide an essential contribution to influenza control and to improving existing vaccination programmes, as well as to the optimisation and planning of health resources and policies.

The Impact of the COVID-19 Pandemic on Influenza Vaccination Attitudes and Actions in Spain's Adult Population

Seasonal influenza is an acute respiratory infection caused by the influenza virus which constitutes a significant public health issue associated with high morbidity and mortality. The aim of this study was to investigate changes in attitudes, perceptions, and practices regarding influenza vaccination in the Spanish adult population during the COVID-19 pandemic, as well as their vaccination intentions, with special attention paid to those over 65 years old and in high-risk groups. To this end, a cross-sectional study was conducted through 2219 telephone interviews, and the results were compared with results obtained a year earlier. Regarding the reasons for deciding to get vaccinated in the 2022/23 season, a significant increase was observed in vaccine confidence (36.7% vs. 42.8%), social responsibility (32.5% vs. 43.8%), and in awareness of the importance of vaccination due to COVID-19 (21.7% vs. 25.4%). Advanced age (OR 2.8, 95% CI 2.0-3.9), belonging to high-risk groups (OR 2.7, 95% CI 2.0-3.7), and prior vaccination (OR 25.3, 95% CI 19.5-32.7) emerged as significant predictors for the intent to receive the influenza vaccine in the 2022/23 season. Continuously observing shifts in perceptions and behaviors related to influenza immunization is crucial to pinpoint factors that may influence the willingness to receive the vaccine and, in this way, design public health strategies that achieve a greater acceptance of it.

Cost-effectiveness analysis of the direct and indirect impact of intranasal live attenuated influenza vaccination strategies in children: alternative country profiles

BACKGROUND

Influenza poses a significant burden on healthcare systems and society, with under-recognition in the paediatric population. Existing vaccination policies (largely) target the elderly and other risk groups where complications may arise.

OBJECTIVE

The goal of this study was to evaluate the cost-effectiveness of annual paediatric vaccination (in 2-17-year-olds) with live attenuated influenza vaccination (LAIV), as well as the protective effect on the wider population in England and Wales (base). The study aimed to demonstrate broad applications of the model in countries where epidemiological and transmission data is limited and that have sophisticated vaccination policies (Brazil, Spain, and Taiwan).

METHODS

The direct and indirect impact of LAIV in the paediatric cohort was simulated using an age-stratified dynamic transmission model over a 5-year time horizon of daily cycles and applying discounting of 3.5% in the base case. Pre-existing immunity structure was based on a 1-year model run. Sensitivity analyses were conducted.

RESULTS

In the base case for England and Wales, the annual paediatric strategy with LAIV was associated with improvements in influenza-related events and quality-adjusted life years (QALYs) lost, yielding an incremental cost per QALY of £6,208. The model was robust to change in the key input parameters. The probabilistic analysis demonstrated LAIV to be cost effective in more than 99% of iterations, assuming a willingness-to-pay threshold of £30,000. Incremental costs per QALY for Brazil were £2,817, and for the cases of Spain and Taiwan the proposed strategy was dominant over the current practice.

CONCLUSION

In addition to existing policies, annual paediatric vaccination using LAIV provides a cost-effective strategy that offers direct and indirect protection in the wider community. Paediatric vaccination strategies using LAIV demonstrated clinical and economic benefits over alternative (current vaccination) strategies in England and Wales as well as Brazil, Spain, and Taiwan.

Coverage and predictors of vaccination against 2012/13 seasonal influenza in Madrid, Spain: analysis of population-based computerized immunization registries and clinical records

We aim to determine 2012–13 seasonal influenza vaccination coverage. Data were analyzed by age group and by coexistence of concomitant chronic conditions. Factors associated with vaccine uptake were identified. We also analyze a possible trend in vaccine uptake in post pandemic seasons.

We used computerized immunization registries and clinical records of the entire population of the Autonomous Community of Madrid, Spain (6 284 128 persons) as data source.

A total of 871 631 individuals were vaccinated (13.87%). Coverage for people aged ≥ 65 years was 56.57%. Global coverage in people with a chronic condition was 15.7% in children and 18.69% in adults aged 15–59 years.

The variables significantly associated with a higher likelihood of being vaccinated in the 2012–13 campaign for the age groups studied were higher age, being Spanish-born, higher number of doses of seasonal vaccine received in previous campaigns, uptake of pandemic vaccination, and having a chronic condition.

We conclude that vaccination coverage in persons aged <60 years with chronic conditions is less than acceptable. The very low coverage among children with chronic conditions calls for urgent interventions. Among those aged ≥60 years, uptake is higher but still far from optimal and seems to be descending in post-pandemic campaigns. For those aged ≥65 years the mean percentage of decrease from the 2009/10 to the actual campaign has been 12%.

Computerized clinical and immunization registers are useful tools for providing rapid and detailed information about influenza vaccination coverage in the population.

The impact of influenza and respiratory syncytial virus on hospitalizations for lower respiratory tract infections in young children: Slovenia, 2006-2011

Background

Influenza and respiratory syncytial viruses (RSV) are important viral pathogens in childhood.

Objectives

Our aim was to estimate the effect of influenza and RSV on excess hospitalizations for acute lower respiratory tract infections (ALRTI) in children aged ≤5.

Methods

Retrospective, population‐based study was performed for five seasons (2006–2011). Slovenian national hospital discharge data and surveillance data were used to estimate the effect of influenza and/or RSV on ALRTI hospitalizations (acute bronchiolitis, pneumonia, and acute bronchitis) using rate difference method.

Results

An excess was observed in average weekly ALRTI hospitalizations per 100 000 among children aged ≤5 in all five seasons during influenza and/or RSV active period. During three seasons, there was higher excess in ALRTI hospitalizations in the period when influenza/RSV cocirculated compared with the RSV period. In pandemic season (2009/2010), the only one without influenza/RSV overlap, excess hospitalization was higher in RSV period. The highest excess of hospitalizations was found among the youngest children (0‐5 months old). In all five seasons, acute bronchiolitis was the most common ALRTI recorded in hospitalized young children.

Conclusions

Respiratory syncytial viruses was leading viral pathogen associated with ALRTI hospitalizations in children aged ≤5. The cocirculation of influenza virus increased the burden of ALRTI hospitalizations especially in seasons with A(H3) predominance.

Influenza vaccination coverage and uptake predictors among Spanish adults suffering COPD

The aim of this study is to compare influenza vaccination coverage among Spaniards aged 40 y or over who suffer from chronic obstructive pulmonary disease (COPD) with those without this illness to identify the factors that influence vaccination uptake among patients with COPD. Data was extracted from the European Health Survey performed in Spain in 2009/10, and analyzed data on 15,355 Spaniards (≥ 40 y of age), of whom 1,309 (8.2% 95%CI 7.7-8.7) had COPD was used. We considered the answer (yes/no) to the question about whether or not the interviewed person had been vaccinated against influenza in the previous flu season. We used the answer to this question as the dependent variable. For independent variables, we analyzed social demographic characteristics, health related variables, and the utilization of health care services. Vaccination coverage among patients with COPD is 49.4% (95% CI: 46.3-52.5%) and 21.3% (95% CI: 20.7-21.9) among people without (p < 0.001). The probability of being vaccinated is three times greater for COPD patients (crude OR = 3.0, 95% CI: 2.6-3.5). Among COPD patients the uptake of vaccination increased with age. Other factors associated with an increase in vaccination coverage were: being male, perceiving one's health as fair or poor, not smoking, and having seen a doctor during the previous month. The rate of flu vaccination among adult Spaniards with COPD is lower than desired. Urgent strategies for increasing vaccination coverage are necessary for COPD sufferers aged under 65 of age and those with unhealthy lifestyles.

Trends in pneumonia and influenza-associated hospitalizations in South Korea, 2002-2005

Pneumonia and influenza are leading causes of morbidity and mortality across the globe. Korea has established the national health-insurance system to cover the entire Korean population since 1989. The aim of this study was to describe the epidemiologic trends in pneumonia and influenza-associated hospitalizations and deaths using the Korean National Health Insurance databases and national vital statistics. During 2002-2005, 989,472 hospitalizations and 10,543 deaths due to pneumonia and influenza were recorded. Eighty-one percent of the hospitalizations were related to diagnoses with unspecified aetiology. The average annual rate of hospitalizations due to pneumonia and influenza was 5.2 per 1,000 people [95% confidence interval (CI) 5.2-5.3], and the hospitalization rate increased by 28% (from 4.5 to 5.8 per 1,000 people) during the four-year study period. In addition, deaths due to pneumonia and influenza increased by 48% (2,829 during 2003, 3,522 during 2004, and 4,192 during 2005). Overall, the national burden of hospitalizations and deaths due to pneumonia and influenza in Korea was high, and it increased for all age-groups during the study period. A comprehensive review of potential interventions by the government authorities should aim to reduce the burden of pneumonia and influenza.

Exploring the effect of biological delays in kinetic models of influenza within a host or cell culture

BACKGROUND

For a typical influenza infection in vivo, viral titers over time are characterized by 1-2 days of exponential growth followed by an exponential decay. This simple dynamic can be reproduced by a broad range of mathematical models which makes model selection and the extraction of biologically-relevant infection parameters from experimental data difficult.

RESULTS

We analyze in vitro experimental data from the literature, specifically that of single-cycle viral yield experiments, to narrow the range of realistic models of infection. In particular, we demonstrate the viability of using a normal or lognormal distribution for the time a cell spends in a given infection state (e.g., the time spent by a newly infected cell in the latent state before it begins to produce virus), while exposing the shortcomings of ordinary differential equation models which implicitly utilize exponential distributions and delay-differential equation models with fixed-length delays.

CONCLUSIONS

By fitting published viral titer data from challenge experiments in human volunteers, we show that alternative models can lead to different estimates of the key infection parameters.

Cost-effectiveness of influenza vaccination of people aged 50-64 years in Australia: results are inconclusive

OBJECTIVE

Influenza cost-effectiveness studies use models for influenza clinical evolution based on a range of assumptions. We explore the importance of these assumptions and its implications in policy decisions.

METHODS

An influenza model was constructed to measure the cost-effectiveness of universal influenza vaccination of people over 50 years compared to current policy to vaccinate people over 65 years in Australia using available epidemiological data. We explored two scenarios, one with an Australian estimate of influenza like illness incidence, and one with a European estimate. Further, we estimated uncertainty of model structure and various parameter assumptions, and compared with a previous study.

RESULTS

The scenario and sensitivity analysis has shown the incremental cost-effectiveness ratio of the proposed compared to current policy varies from $112,000 to $6,000 per DALY. The model structure, parameter assumptions and limitations of existing epidemiological data lead to extensive unaccounted uncertainties in previous studies.

CONCLUSION

The lack of influenza epidemiological data makes the influenza cost-effectiveness studies that compare the universal influenza vaccinations of people over 50 years to current policy unreliable.

IMPLICATIONS

It is imperative to appraise unreliability of influenza cost-effectiveness studies in policy decisions. Research to acquire more data on influenza uncertainties in Australia should be funded.

Influenza vaccination coverage among Spanish children, 2006

OBJECTIVES

Traditionally, influenza is not considered to be a serious disease in healthy children. However, for vulnerable populations, such as young children and those with chronic medical conditions, influenza can lead to serious complications and even death. This study aimed to assess vaccination coverage among Spanish children under 16 years of age in 2006, and to describe the factors associated with vaccination.

STUDY DESIGN

Cross-sectional survey.

METHODS

In total, 8851 records of children included in the Spanish National Health Survey for 2006 were analysed. The reply ('yes' or 'no') to the question: 'Did you have a flu shot in the latest campaign?' was used as a dependent variable. Influenza vaccine coverage was calculated as the percentage of individuals aged 6 months to 16 years whose parents reported that they had been vaccinated against influenza in the most recent campaign. The influence of sociodemographic variables on vaccination and the presence of associated chronic diseases (asthma and/or diabetes) were also analysed.

RESULTS

Vaccination coverage among Spanish children in 2006 was 6.82%: 19.43% in children with associated conditions (asthma and/or diabetes), and 5.81% in healthy children. The only factor significantly associated with influenza vaccination in children with associated conditions was household income; children with a lower household monthly income were more likely to have been vaccinated against influenza than children with a higher household monthly income (odds ratio 1.96). In children for whom vaccination is not indicated, the probability of being vaccinated against influenza was greater in those whose parents were not university graduates.

CONCLUSION

Influenza vaccination coverage in Spanish children is low. Socio-economic inequalities continue to be a factor at the time of vaccination.

Predictors of influenza vaccination in adults with chronic bronchitis

Influenza vaccination is recommended for people with chronic bronchitis (CB) because they have a higher risk of influenza-related complications, hospitalizations, and death during seasonal influenza epidemics. This study sought to evaluate influenza vaccination coverage among adults with CB and analyze the factors (predictors) linked to compliance with vaccination recommendations. Individual data from adults aged > or = 40 years included in the Spanish Health Survey conducted in 2006 were used. Subjects were classified as chronic bronchitis sufferers if they answered affirmatively to the question: "has your doctor told you that you are currently suffering from chronic bronchitis?". To assess influenza vaccination status we used the question, "did you have a flu shot in the latest campaign?". Independent variables analyzed included sociodemographic, health-related variables, self-reported presence of other concomitant chronic diseases, and use of health-care services. The percentage of subjects who were reported to be suffering from CB was 6.6% (N=1320, 95% CI 6.2-6.9%). The influenza vaccination coverage among CB sufferers was 63.6% compared with 48.6% for nonsufferers (p<0.05). The predictors significantly associated with a higher likelihood of receiving the vaccine among adult CB sufferers were: higher age; male gender; nonsmoker or ex-smoker status; doing physical exercise; and suffering from concomitant asthma or diabetes. We conclude that influenza vaccination coverages among Spanish adults suffering from CB are below desirable levels; thereby making it necessary for strategies to be implemented aimed at improving the use of influenza vaccine among such patients.