Understanding the Barriers and Attitudes toward Influenza Vaccine Uptake in the Adult General Population: A Rapid Review

Nonstructural barriers to adult vaccination

Adult vaccination coverage remains low, despite vaccine recommendations, improved access, and reimbursement. Low vaccination coverage and an aging population at higher risk from vaccine-preventable diseases lead to preventable disability and deaths, straining healthcare systems. An Advisory Board meeting was, therefore, held to identify non-structural barriers to adult vaccination and discuss potential solutions to increase uptake. Many non-structural factors can influence vaccine uptake, such as heterogeneity in the population, (fear of) vaccine shortages, incentives, or mandates for vaccination, understanding of disease burden and personal risks, time and opportunity for healthcare providers (HCPs) to discuss and deliver vaccines during general practice or hospital visits, trust in the health system, and education. To address these barriers, push-pull mechanisms are required: to pull patients in for vaccination and to push HCP performance on vaccination delivery. For patients, the focus should be on lifelong prevention and quality of life benefits: personal conversations are needed to increase confidence and knowledge about vaccination, and credible communication is required to build trust in health services and normalize vaccination. For providers, quality measurements are required to prioritize vaccination and ensure opportunities to check vaccination status, discuss and deliver vaccines are not missed. Financial and quality-based incentives may help increase uptake.

Drivers and barriers of seasonal influenza vaccination 2015/16 & 2019/20 to 2022/23 - a survey on why most Norwegians don't get the flu vaccine

BACKGROUND

This study aimed to explore the reasons adults in the general population, influenza risk groups (RGs) and health care workers (HCWs) in Norway give for their vaccination choices and whether these reasons vary between groups or over time in order to further improve influenza vaccination coverage.

METHODS

Respondents of a nationally representative telephone survey conducted by Statistics Norway were asked "What was the most important reason why you did/did not get vaccinated?". The question on influenza non-vaccination was included in 2016 and in 2020 to 2023 and the question on influenza vaccination in 2021 to 2023.

RESULTS

The study included 9 705 individuals aged 18-79 years. Influenza vaccination coverage in the RGs increased from 20.6% in 2016 to 63.1% in 2022, before a reduction to 58.3% in 2023. Common reasons for non-vaccination were similar in all groups. The most cited reasons were "no need" for the vaccine and "no specific reason", followed by "not recommended/offered the vaccine", "worry about side effects" and "vaccine refusal". The most frequent reasons for vaccination among the general population and RGs were protection against influenza and belonging to a RG, while the most frequent responses among HCWs were being offered the vaccine at work/work in health care, followed by a desire for protection against influenza. Receiving a vaccine recommendation from a health professional was mentioned in all groups. We also observed that the proportion reporting "no need" for the vaccine decreased over time, especially among HCWs, and that the proportions reporting vaccine refusal and worry about side effects as reasons for non-vaccination were temporarily reduced during the COVID-19 pandemic.

CONCLUSIONS

The general population and RGs cite protection against influenza as their primary incentive for vaccination, while HCWs mainly refer to their professional role or workplace vaccination. For non-vaccination we see a similar pattern in all groups, with "no need" and "no specific reason" as the main reasons. Of note, worry about side effects and vaccine refusal is as frequent among HCWs as in other groups. Continued efforts to maintain and increase vaccine confidence are needed.

Repeated vaccination does not appear to significantly weaken the protective effect of influenza vaccine in the elderly: A test-negative case-control study in China

BACKGROUND

The impact of repeated influenza vaccination on vaccine effectiveness has been a topic of debate. Conducting more multinational, multicenter studies in different influenza seasons is crucial for a better understanding of this issue. There is a lack of comprehensive related research reports in China.

METHODS

Using the Regional Health Information Platform, we conducted a test-negative case-control study to evaluate the impact of repeated vaccination on the prevention of laboratory-confirmed influenza in individuals aged 60 and above in Ningbo during four influenza seasons from 2018-19 to 2021-22. Influenza-positive cases and negative controls were matched in a 1:1 ratio based on the visiting hospital and the date of influenza testing. Propensity score adjustment and multivariable logistic regression were used to estimate risk and address confounding effects.

RESULTS

During the study period, a total of 30,630 elderly patients underwent influenza virus nucleic acid or antigen testing. After exclusions, we included 1976 cases of influenza-positive and 1976 cases of influenza-negative controls. Multivariable logistic regression analysis revealed that individuals receiving the vaccine in two consecutive seasons did not exhibit a significantly increased risk of influenza illness compared to those receiving the vaccine only in the current season (adjusted odds ratio: 1.22, 95% confidence interval: 0.94-1.58). However, the risk of influenza illness was found to be elevated in individuals who received the vaccine only in the previous season (adjusted odds ratio: 1.56, 95% confidence interval: 1.15-2.10) and even further elevated in those who had not received the vaccine in either of the consecutive two seasons (adjusted odds ratio: 3.39, 95% confidence interval: 2.80-4.09).

CONCLUSIONS

Regardless of the vaccination history in the previous season, receiving the current season influenza vaccine is the best choice for the elderly population. Our study supports the initiative to vaccinate elderly individuals against influenza annually.

Increasing Influenza Vaccination Rates among Patients with Type 2 Diabetes Mellitus in Chongqing, China: A Cross-Sectional Analysis Using Behavioral and Social Drivers Tools

BACKGROUND

Influenza vaccination is essential for type 2 diabetes mellitus (T2DM) patients due to their higher risks of severe complications and mortality from influenza. This study investigated the willingness of T2DM patients in Chongqing, China, to receive the influenza vaccination during the 2023/2024 season, using behavioral and social drivers (BeSD) tools to improve vaccination uptake in this high-risk group.

METHODS

A multi-stage sampling method was used to select participants, and face-to-face surveys were conducted in community health centers between March 1 and May 1, 2023. Binary logistic regression was used to analyze the factors influencing vaccination willingness, and standardized scores identified barriers and drivers.

RESULTS

Among 1672 T2DM patients, 11.7% had been vaccinated during the 2022/2023 season, and 59.6% were willing to receive the vaccination in the 2023/2024 season. Higher willingness was associated with ethnic minorities (odds ratio [OR], 3.18, 95% confidence interval [CI]: 1.58-6.39), being unemployed individuals (OR 2.69, 95% CI: 1.60-4.52), higher monthly household income per capita (OR 2.72, 95% CI: 1.65-4.50), having diabetes complications (OR 1.76, 95% CI: 1.23-2.51), sufficient vaccine knowledge (OR 1.87, 95% CI: 1.48-2.37), and previous vaccination (OR 7.75, 95% CI: 4.83-12.44). Concerning BeSDs, fear of infecting friends or family members and trust in vaccine efficacy were the predominant drivers, while high vaccine costs were the greatest barrier.

CONCLUSIONS

Future strategies should focus on improving vaccine knowledge, supporting healthcare workers and peer recommendations, and enhancing vaccination policies. Key interventions such as health education among high-risk groups, such as unemployed individuals, advocacy campaigns, pay-it-forward strategies, and policies for free vaccination could improve coverage in Chongqing.

Socio-economic inequalities in the use of flu vaccination in Europe: a multilevel approach

BACKGROUND

The European-wide statistics show that the use of flu vaccination remains low and the differences between countries are significant, as are those between different population groups within each country. Considerable research has focused on explaining vaccination uptake in relation to socio-economic and demographic characteristics, health promotion and health behavior factors. Nevertheless, few studies have aimed to analyze between-country differences in the use of flu vaccination for the EU population. To address this gap, this study examines the socio-economic inequalities in the use of influenza vaccination for the population aged 15 years and over in all 27 EU Member States and two other non-EU countries (Iceland and Norway).

METHODS

Using data from the third wave of European Health Interview Survey (EHIS) 2019, we employed a multilevel logistic model with a random intercept for country, which allows controlling simultaneously the variations in individuals' characteristics and macro-contextual factors which could influence the use of flu vaccination. In addition, the analysis considers the population stratified into four age groups, namely adolescents, young adults, adults and elderly, to better capture heterogeneities in flu vaccination uptake.

RESULTS

The main findings confirm the existence of socio-economic inequalities between individuals in different age groups, but also of significant variation between European countries, particularly for older people, in the use of influenza vaccination. In this respect, income and education are strong proxy of socio-economic status associated with flu vaccination uptake. Moreover, these disparities within each population group are also explained by area of residence and occupational status. Particularly for the elderly, the differences between individuals in vaccine utilization are also explained by country-level factors, such as the type of healthcare system adopted in each country, public funding, personal health expenditure burden, or the availability of generalist practitioners.

CONCLUSIONS

Overall, our findings reveal that vaccination against seasonal influenza remains a critical public health intervention and bring attention to the relevance of conceiving and implementing context-specific strategies to ensure equitable access to vaccines for all EU citizens.

Nanoparticle-Mediated Mucosal Vaccination: Harnessing Nucleic Acids for Immune Enhancement

Recent advancements in in vitro transcribed mRNA (IVT-mRNA) vaccine manufacturing have attracted considerable interest as advanced methods for combating viral infections. The respiratory mucosa is a primary target for pathogen attack, but traditional intramuscular vaccines are not effective in generating protective ion mucosal surfaces. Mucosal immunization can induce both systemic and mucosal immunity by effectively eliminating microorganisms before their growth and development. However, there are several biological and physical obstacles to the administration of genetic payloads, such as IVT-mRNA and DNA, to the pulmonary and nasal mucosa. Nucleic acid vaccine nanocarriers should effectively protect and load genetic payloads to overcome barriers i.e., biological and physical, at the mucosal sites. This may aid in the transfection of specific antigens, epithelial cells, and incorporation of adjuvants. In this review, we address strategies for delivering genetic payloads, such as nucleic acid vaccines, that have been studied in the past and their potential applications.

Podcast: Need for Quality Evidence for Decision-Making on Seasonal Influenza Vaccines

Seasonal influenza is usually considered an acute respiratory infection with a full recovery within a week. In addition to the traditional outcomes, there is now evidence of indirect effects in terms of neurological and functional complications. Major organ systems can be affected, underlining the need for preventative measures against infection. The aim of this podcast, featuring Dr. Ann Falsey, Dr. Stefania Maggi, and Dr. Tor Biering-Sørensen, is to outline influenza complications beyond acute respiratory disease, as well as discussing the need for quality of evidence when evaluating influenza vaccines. Assessing the benefits of vaccination can be challenging. To ensure a high quality of evidence, the innovative randomization of patients within the study design to avoid bias and the assessment of additional outcomes beyond immunogenicity as well as the inclusion of a broad population-including frail or vulnerable individuals-are essential. Studies leveraging nationwide registries such as the DANFLU-2 trial in Denmark highlight the advantages of a digitalized healthcare system for conducting large-scale randomized trials. Furthermore, large-scale trials such as the Gravenstein study have supplied a sizable body of evidence supporting the use of high-dose influenza vaccine in older adults. In conclusion, achieving a high quality of evidence is key for decision-making on seasonal influenza vaccines.

Immune Cells, Gut Microbiota, and Vaccines: A Gender Perspective

The development of preventive and therapeutic vaccines has played a crucial role in preventing infections and treating chronic and non-communicable diseases, respectively. For a long time, the influence of sex differences on modifying health and disease has not been addressed in clinical and preclinical studies. The interaction of genetic, epigenetic, and hormonal factors plays a role in the sex-related differences in the epidemiology of diseases, clinical manifestations, and the response to treatment. Moreover, sex is one of the leading factors influencing the gut microbiota composition, which could further explain the different predisposition to diseases in men and women. In the same way, differences between sexes occur also in the immune response to vaccines. This narrative review aims to highlight these differences, focusing on the immune response to vaccines. Comparative data about immune responses, vaccine effectiveness, and side effects are reviewed. Hence, the intricate interplay between sex, immunity, and the gut microbiota will be discussed for its potential role in the response to vaccination. Embracing a sex-oriented perspective in research may improve the efficacy of the immune response and allow the design of tailored vaccine schedules.

COVID-19 and flu vaccination in Romania, post pandemic lessons in healthcare workers and general population

BACKGROUND

Influenza and corona viruses generate vaccine preventable diseases and have pandemic potential, frequently dramatic. A co-infection with these viruses, may be a new worldwide threat, researchers name it flurona. The aim of our study is to assess flu and COVID-19 Romanian vaccination for 2022-2023 season and the factor associated with higher odds to receive flu and COVID-19 vaccine.

METHODS

An analytical cross-sectional observational survey was conducted in the general population; a self-administered questionnaire was used.

RESULTS

1056 responders were analyzed, mean age 32.08 ±13.36 years (limits:18-76), majority, 880 (83.33%), from urban areas, 608 (57.58%), high school graduated, 400 (37.88%) parents. More than half of the responders were healthcare workers, 582 (55.11%), also considered study population. In the study group, 796 (73.37%) responders consider flurona vaccination useful; and 872 (82.57%) responders consider that no sanctions are needed for not flurona vaccinating. In the 2022-2023 season, 162 (15.34%) responders vaccinated against the flu and 300 (28.41%) against COVID-19. The factor associated with higher odds to receive flu and COVID-19 vaccine was the habit of flu vaccination: for flu (OR = 58.43; 95% CI: (34.95-97.67)) and for COVID-19 (OR = 1.67; 95% CI: (1.21-2.31)). Other factors such as having university degree (OR = 1.46; 95% CI: (1.08-1.98)) and being a healthcare worker, (OR = 1.41; 95% CI: (1.07-1.87)) were influencing factors only for adult COVID-19 vaccination in the 2022-2023 season. In the parents' group, in 2022-2023 season, only 48 (12%) vaccinated their children against the flu and 68 (17%) against COVID-19, mostly parents that vaccinated themselves, p<0.001. In the 2022-2023 season, there were only 82 (7.65%) responders vaccinated against both diseases. Logistic regression analysis showed that no factor analyzed influenced the flurona vaccinated parent's decision to vaccinate their children for flu and for COVID-19.

CONCLUSIONS

In the season 2022-2023, in Romania, the vaccination against flu and COVOD-19 is low, in adults and children as well. More efforts must be done to increase flurona vaccination, public health educational programs are strongly needed. Children, that are at greater risk when co-infecting with these viruses, must be vaccinated, school vaccination programs should be considered.

Italian oncologists and vaccinations against infectious diseases: Results of a survey of the Italian Association of Medical Oncology

BACKGROUND

Patients with cancer present a higher risk of vaccine-preventable diseases. Recommended vaccinations are the most cost-effective measure to reduce the risk of transmission and related complications. Nevertheless, vaccination rates are inadequate. Oncologists have a central role in tailored vaccine communication to their patients. We present the results of a survey conducted by AIOM in 2022, focusing on the perception of the problem by oncologists.

MATERIALS AND METHODS

An anonymous 31-item online questionnaire was shared on 15 September 2022 on the AIOM website. The objectives of this survey were to examine the perception of Italian oncologists on vaccine-preventable diseases and the main available vaccines, their attitude towards recommending vaccines and the COVID-19 pandemic impact on their habits regarding vaccine-preventable diseases.

RESULTS

Between September 2022 and January 2023, 114 medical oncologists (5% of the members) completed the anonymous questionnaire. At the first oncological visit, only 30% of respondents usually propose a vaccination schedule to all their patient, 41% do not usually discuss vaccinations at the first visit and 29% recommend vaccines exclusively to specific categories of patients. For 56% of respondents, patients are more aware of the benefits of vaccines, whereas 36% reported that patients are worried of receiving too many vaccines.

CONCLUSION

This is the first survey conducted among Italian oncologists to better understand the perception and attitudes towards the vaccination. It highlights the urgent issues of educating and training oncologists in vaccine-preventable diseases and vaccine awareness and the need to build (or implement) a network of multidisciplinary collaborations.

Health beliefs and attitudes toward Influenza and COVID-19 vaccination in Portugal: a study using a mixed-method approach

Introduction

Vaccination is one of the most effective population strategies to prevent infectious diseases and mitigate pandemics, and it is important to understand vaccine uptake determinants since vaccine hesitancy has been increasing for the past few decades. The Health Belief Model (HBM) has been widely used for understanding vaccination behavior. The current study aimed to assess influenza vaccine (IV) non-uptake and attitudes toward COVID-19 vaccination, two important respiratory diseases with similar symptoms, and routes of transmission in the Portuguese population.

Methods

We conducted a cross-sectional study using a panel sample of randomly chosen Portuguese households. A total of 1,050 individuals aged 18 years and over responded to a telephone or online questionnaire. Through a mixed-method approach, we employed thematic content analysis to describe reasons for not taking the IV, considering the HBM dimensions, and quantitative statistical analysis to estimate IV and COVID-19 vaccine coverage.

Results

The IV uptake for the overall population was 30.7% (CI 95%: 26.5, 35.2). Susceptibility was found to be a main factor for IV non-uptake, followed by barriers, such as stock availability and fear of adverse effects. The uptake of the COVID-19 vaccine was very high in the study population (83.1%, CI 95%: 13.6%-20.9%). There was a high perception of COVID-19-associated severity and fear of the consequences. Individuals who reported IV uptake seemed to perceive a higher severity of COVID-19 and a higher benefit of taking the COVID-19 vaccine for severe complications.

Discussion

Thus, the population does not seem to consider influenza to be a health risk, as opposed to COVID-19, which is considered to be a possibly severe disease. The association between IV uptake and COVID-19 perceptions highlights that an overall attitude toward vaccination in general may be an important individual determinant.

Influvac Tetra: clinical experience on safety, efficacy, and immunogenicity

INTRODUCTION

This paper summarizes the safety and immunogenicity data of Influvac Tetra across all age groups starting from 6 months of age, obtained during its clinical development program.

AREAS COVERED

The article covers the clinical development program of Influvac Tetra based on five registration studies that included different age groups, different comparators, and participants from Europe and Asia. Safety and immunogenicity were assessed in all studies and in one study, the efficacy of Influvac Tetra was assessed.

EXPERT OPINION

Seasonal influenza is a vaccine-preventable disease that can cause serious complications. Several types of influenza vaccines are available, including egg-based (standard dose, high dose, and adjuvanted), cell-based, and recombinant. The COVID-19 pandemic has stimulated innovation in the development such as mRNA vaccines. However, these vaccines are still in development and the true value still has to be proven. Regardless of the type of vaccine, it is also important to increase overall vaccination coverage. ECDC recommends that EU Member States implement action plans and policies aimed at reaching 75% coverage in at-risk groups and healthcare workers. Even so, vaccine coverage is still far from recommended.

Immunizing hearts: exploring the vaccination frontier in heart failure management

Heart failure (HF) is a widespread clinical condition that affects numerous individuals globally and is a leading cause of hospitalization, particularly in the elderly population. Despite efforts to manage HF using various pharmacological and nonpharmacological interventions, mortality and hospitalization rates remain alarmingly high. Preventive vaccination has emerged as a key measure endorsed by cardiology societies for reducing the morbidity and mortality associated with HF. This study undertakes an extensive review of existing literature to explore the role of vaccination in managing HF, focusing specifically on the immunological pathways involved and potential benefits offered by immunization in this context. This article highlights the role of various vaccines, including influenza, pneumococcal, and COVID-19 vaccines, in reducing HF-related hospitalization, mortality, and overall disease burden. Additionally, this article will delve into specific vaccines that have shown promise in HF management, such as influenza, pneumococcal, and COVID-19 vaccines, along with the rationale for their use, clinical trials, meta-analyses, and real-world data supporting their effectiveness in patients with HF. This article also considers potential challenges and obstacles to widespread vaccination in individuals with HF, which include vaccine hesitancy, accessibility, and adverse events related to vaccines.

Flu vaccination coverage in Italy in the COVID-19 era: A fuzzy functional k-means (FFKM) approach

BACKGROUND

In Europe, flu vaccination coverage has decreased, and there are complex barriers to overcome to vaccinate against flu. Many studies have been conducted to estimate vaccination coverage. The COVID-19 pandemic threatens to disrupt immunization programs in many countries, including Italy, where vaccination against the flu is recommended but not mandatory. This paper aims to understand changes in flu vaccine uptake in Italian regions.

METHODS

Using functional data analysis and fuzzy functional k-means clustering, we investigated changes in flu vaccine coverage in Italian regions before (2010-2019) and after (2020-2022) the COVID-19 vaccination period.

RESULTS

The period of COVID-19 pandemic brought an increase in vaccine coverage globally. Elbow's method determined that the optimal number of clusters in vaccination uptake is 2. Apulia, Basilicata, Emilia Romagna, Liguria, Molise, Tuscany, and Umbria in 2019 belong less to the group with low flu vaccination uptake (G1) but increase their tendency to belong to this group over time: they decrease their propensity to be vaccinated for flu. For others, it seems that COVID-19 served as a push to increase flu vaccination coverage rates. Sicily appears to be the region that has responded best to the pandemic, changing its membership value from 2019 to 2022.

CONCLUSION

The present study highlights that the COVID-19 era has resulted in a higher flu vaccination coverage rate. Moreover, the regional level's improvement or worsening in flu vaccination coverage rate is not affected by the historical gap and socio-cultural and economic differences prevailing among Italian regions.

Understanding the Global Burden of Influenza in Adults Aged 18-64 years: A Systematic Literature Review from 2012 to 2022

INTRODUCTION

Adults aged 18-64 years comprise most of the working population, meaning that influenza infection can be disruptive, causing prolonged absence from the workplace, and reduced productivity and the ability to care for dependents. Influenza vaccine uptake is relatively low, even among the older adults in this population (i.e., aged 50-64 years), reflecting a lack of perceived need for vaccination. This systematic literature review (SLR) aimed to characterize the global burden of influenza in the 18-64 years population.

METHODS

An electronic database search was conducted and supplemented with conference and gray literature searches. Eligible studies described at least one of clinical, humanistic, or economic outcomes in adults aged 18-64 years and conducted across several global regions. Included studies were published in English, between January 1, 2012, and September 20, 2022.

RESULTS

A total of 40 publications were included, with clinical, humanistic, and economic outcomes reported in 39, 5, and 15, respectively. Risk of influenza-associated clinical outcomes were reported to increase with age among the 18-64 years population, including hospitalizations (Yamana et al. in Intern Med 60:3401-3408, 2021; Derqui et al. in Influenza Other Respir Viruses 16:862-872, 2022; Fuller et al. in Influenza Other Respir Viruses 16:265-275, 2022; Ortiz et al. in Crit Care Med 42:2325-2332, 2014; Yandrapalli et al. in Ann Transl Med 6:318, 2018; Zimmerman et al. in Influenza Other Respir Viruses 16:1133-1140, 2022). ICU admissions, mortality, ER/outpatient visits, and use of mechanical ventilation were recorded. Adults aged 18-64 years with underlying comorbidities were at higher risk of influenza-related hospitalizations, ICU admission, and mortality than otherwise healthy individuals. Length of hospital stay increased with age, although a lack of stratification across other economic outcomes prevented identification of further trends across age groups.

CONCLUSIONS

High levels of hospitalization and outpatient visits demonstrated a clinical influenza-associated burden on patients and healthcare systems, which is exacerbated by comorbidities. Considering the size and breadth of the general population aged 18-64 years, the limited humanistic and economic findings of this SLR likely reflect an underreported burden. Greater investigation into indirect costs and prolonged absenteeism associated with influenza infection is required to fully understand the economic burden in this population.

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.