[Effectiveness of flu vaccine in the prevention of severe cases. Season 2018-2019]

[Determinants of influenza vaccination in people over 65 years of age: A systematic review]

Low influenza vaccination rates among specific risk groups contribute to the burden of disease and remain a major public health challenge. Therefore, the purpose of this review was to provide the most recent evidence on the determinants of influenza vaccination in people over 65years of age. During the review process, we followed the recommendations for PRISMA systematic reviews. The bibliographic search was carried out in databases Cumulative Index to Nursing and Allied Health Literature (CINAHL), SCOPUS, MedLine / PubMed, Cochrane, Google Scholar, with free and controlled language and the search terms MeSh: Vaccination Coverage, Health Communication, Aged, Influenza Vaccines by combining them with the Boolean operators AND and OR. The search was limited to articles published between 2019-2024. Seven original research articles were included, of which observational and cross-sectional studies were identified as the main type of study. The topic of study represents education, the recruitment of the vulnerable population and the detection of sociodemographic factors that affect vaccination coverage. The findings of this review suggest that it would be beneficial to take into account communication, education and recruitment as determining factors of influenza vaccination in those over 65years of age. In this sense, effective strategies could be implemented to increase vaccination coverage in the most vulnerable population and improve future vaccination campaigns.

Influenza vaccination mitigates severe complications in hospitalized patients: A ten-year observational study, Spain, 2009-2019

BACKGROUND

Influenza epidemics annually impact a substantial portion of adults worldwide, leading to numerous hospitalizations and fatalities. While the primary goal of vaccination is to prevent influenza virus infection, breakthrough infections can still occur despite vaccination. Evaluating the vaccine effectiveness in preventing severe cases among hospitalized patients is crucial for enhancing vaccination strategies.

METHODS

This single-center, observational, cross-sectional, and retrospective study analyzed data from 1,357 patients admitted to La Paz University Hospital for influenza infection between 2009 and 2019. Patients' demographics, clinical variables, comorbidities, vaccination status, and influenza-related outcomes were assessed. Logistic regression analysis was performed to determine the vaccine-independent protective effects.

RESULTS

Influenza vaccination independently prevented severe complications, including pneumonia, bacterial superinfection, acute respiratory distress syndrome, and multiple organ failure in hospitalized patients (odds ratio = 0.61, 95% confidence interval: 0.47-0.76). Vaccinated patients had significantly lower intensive care unit admission rates (odds ratio = 0.42, 95% confidence interval: 0.18-0.92). However, there were no significant differences in mortality rates between vaccinated and unvaccinated patients (P = .385).

CONCLUSIONS

Our study provides robust evidence supporting the influenza vaccine protective effect against severe outcomes in hospitalized patients during epidemic flu. Vaccination is associated with a significant reduction in severe complications and intensive care unit admissions, emphasizing its importance as a preventive measure. Improving vaccination coverage, especially in specific comorbidities and age groups, could further enhance the vaccine effectiveness in preventing severe influenza cases.

Influenza and COVID-19 co-infection and vaccine effectiveness against severe cases: a mathematical modeling study

Background

Influenza A virus have a distinctive ability to exacerbate SARS-CoV-2 infection proven by in vitro studies. Furthermore, clinical evidence suggests that co-infection with COVID-19 and influenza not only increases mortality but also prolongs the hospitalization of patients. COVID-19 is in a small-scale recurrent epidemic, increasing the likelihood of co-epidemic with seasonal influenza. The impact of co-infection with influenza virus and SARS-CoV-2 on the population remains unstudied.

Method

Here, we developed an age-specific compartmental model to simulate the co-circulation of COVID-19 and influenza and estimate the number of co-infected patients under different scenarios of prevalent virus type and vaccine coverage. To decrease the risk of the population developing severity, we investigated the minimum coverage required for the COVID-19 vaccine in conjunction with the influenza vaccine, particularly during co-epidemic seasons.

Result

Compared to the single epidemic, the transmission of the SARS-CoV-2 exhibits a lower trend and a delayed peak when co-epidemic with influenza. Number of co-infection cases is higher when SARS-CoV-2 co-epidemic with Influenza A virus than that with Influenza B virus. The number of co-infected cases increases as SARS-CoV-2 becomes more transmissible. As the proportion of individuals vaccinated with the COVID-19 vaccine and influenza vaccines increases, the peak number of co-infected severe illnesses and the number of severe illness cases decreases and the peak time is delayed, especially for those >60 years old.

Conclusion

To minimize the number of severe illnesses arising from co-infection of influenza and COVID-19, in conjunction vaccinations in the population are important, especially priority for the elderly.

Effectiveness of influenza vaccine in preventing severe cases of influenza: Season 2022/2023

INTRODUCTION

Influenza poses a significant burden in terms of morbidity and mortality, with vaccination being one of the most effective measures for its prevention. Therefore, the aim of this study is to determine the effectiveness of the influenza vaccine in preventing cases of severe influenza in patients admitted to a tertiary hospital during the 2022/23 season.

METHODS

Case-control study. All hospitalised patients with a positive result in an RT-PCR for influenza were included. Those who met the criteria for a severe case (pneumonia, sepsis, multi-organ failure, admission to ICU or exitus) were considered cases. Those who did not meet these criteria were considered controls. Vaccine effectiveness (VE) to prevent severe cases and its 95% confidence interval were calculated.

RESULTS

A total of 403 patients were admitted with confirmed influenza. Of these, 98 (24.3%) developed severe influenza. Of the total, 50.6% were men and 47.1% were over 65 years of age. VE adjusted for influenza type, age and certain comorbidities was 40.6% (-21.9 to 71.1). In a segmented analysis, influenza vaccine was effective in preventing severe cases in all categories. It was particularly relevant in the 65+ age group (VEa = 60.9%; -2.0 to 85.0) and in patients with influenza A (VEa = 56.7%; 1.5-80.9).

CONCLUSION

Influenza vaccination markedly reduced the occurrence of severe cases of influenza in hospitalised patients, therefore, it remains the main strategy to reduce morbidity and mortality and associated costs.

[Adaptation and validation of the MoVac-flu scale on motivation towards the flu vaccine]

OBJECTIVE

To translate, adapt and validate the psychometric properties of MoVac-flu scale in order to be used in Spanish.

METHOD

The present research was an analytical observational study of cross-cultural adaptation and validation into Spanish of the MoVac-flu scale. It has been carried out between the months of March and July 2022. The sample size was 142 people who were obtained by consecutive sampling. The processes used for the adaptation have been translation, validation by a committee of experts, back-translation and pilot test. For validation, the psychometric properties of reliability, internal consistency, appearance validity, content validity, utility and ceiling-floor effect have been verified.

RESULTS

The internal consistency of the MoVac-flu scale in its version translated into Spanish was high, showing a McDonald's ω of 0.914.

CONCLUSIONS

The MoVac-flu scale in Spanish allows to measure the degree of motivation towards vaccination against influenza in the adult population.

[Effectiveness of the influenza vaccine in the prevention of influenza in people over 65 years of age]

INTRODUCTION

Influenza is one of the diseases with the greatest epidemiological impact and of maximum relevance in the management of health services. The flu vaccine can have great variability each season, so our objective was to find out the effectiveness of the flu vaccine for the 2017/2018 season for the prevention of severe cases of flu in people over 65 years of age in a 385-bed acute general hospital.

MATERIAL AND METHOD

Study of cases and controls. All hospitalized patients with laboratory-confirmed influenza older than 65 years during the 2017/2018 season were included. Those who met the criteria for a severe case of influenza were considered cases. Those who did not meet the severity criteria were considered controls. Factors associated with the development of severe influenza were calculated.

RESULTS

The median age was 68 years (SD 91.87). The attack rate was 0.23 per hundred inhabitants and the vaccine effectiveness was 38%. The vaccinated and unvaccinated groups were different in terms of age (p < 0.0481). Vaccination status against severe influenza was found to be an independent protective factor (OR = 0.840; 0.746-0.913).

CONCLUSIONS

The effectiveness of influenza vaccination provided greater protection against infection and reduced the severity of influenza in older hospitalized patients. These findings should be taken into account to improve vaccination strategies and achieve better vaccination coverage in the population at risk.

Costs and Factors Associated with Hospitalizations Due to Severe Influenza in Catalonia (2017-2020)

This study aimed to estimate the cost and factors associated with severe hospitalized patients due to influenza in unvaccinated and vaccinated cases. The study had a cross-sectional design and included three influenza seasons in 16 sentinel hospitals in Catalonia, Spain. Data were collected from a surveillance system of influenza and other acute respiratory infections. Generalized linear models (GLM) were used to analyze mean costs stratified by comorbidities and pregnancy. Multivariate logistic models were used to analyze bacterial coinfection, multi-organ failure, acute respiratory distress syndrome, death and ICU admission by season and by vaccination status. Costs of ICU, hospitalization and total mean costs were analyzed using GLM, by season and by vaccination status. All models were adjusted for age and sex. A total of 2742 hospitalized cases were included in the analyses. Cases were mostly aged ≥ 60 years (70.17%), with recommended vaccination (86.14%) and unvaccinated (68.05%). The ICU admission level was statistically significant higher in unvaccinated compared to vaccinated cases. Costs of cases with more than or equal to two comorbidities (Diff = EUR - 1881.32), diabetes (Diff = EUR - 1953.21), chronic kidney disease (Diff = EUR - 2260.88), chronic cardiovascular disease (Diff = EUR - 1964.86), chronic liver disease (Diff = EUR - 3595.60), hospitalization (EUR 9419.42 vs. EUR 9055.45), and total mean costs (EUR 11,540.04 vs. 10,221.34) were statistically significant higher in unvaccinated compared to vaccinated patients. The influenza vaccine reduces the costs of hospitalization. There is a need to focus strategies in recommended vaccination groups.

[Effectiveness of influenza vaccine in preventing severe influenza]

INTRODUCTION

Influenza is one of the diseases with the greatest epidemiological impact and the greatest relevance in the management of health services. The flu vaccine can have great variability each season, so our objective was to know the effectiveness of the flu vaccine for the 2017/2018 season for the prevention of severe cases of flu in a general acute hospital in 385 beds.

MATERIAL AND METHOD

Case control study. All hospitalized patients with laboratory confirmed influenza during the 2017/2018 season were included. Those who met the criteria for a severe case of influenza were considered cases. Those that did not meet the severity criteria were considered controls. The factors associated with the development of severe influenza were calculated.

RESULTS

The effectiveness adjusted by age group and comorbidity was 60.7% (20.5-80.5). The vaccinated and unvaccinated groups were different in terms of age (P<.0381). The highest proportion of cases were concentrated in those over 65 years of age (45.5%). Vaccination status against severe influenza was found to be an independent protective factor (OR=.746; .694-.831).

CONCLUSIONS

The effectiveness of influenza vaccination provided greater protection against infection and reduced the severity of influenza in hospitalized patients. These findings should be considered to improve vaccination strategies and achieve better vaccination coverage in the population at risk.