Factors associated with influenza vaccination coverage among the elderly in South Korea: the Fourth Korean National Health and Nutrition Examination Survey (KNHANES IV)

The effectiveness of influenza vaccine among elderly Chinese: A regression discontinuity design based on Yinzhou regional health information platform

In China, a free influenza vaccination policy is being implemented among individuals aged 70 years and over in Zhejiang province during the COVID-19 pandemic. The objective was to assess the effectiveness of influenza vaccine in reducing hospitalization and mortality in the elderly. We used data from the Regional Health Information Platform in Yinzhou located in Zhejiang province and applied a regression discontinuity design to estimate the intention-to-treat effect on admission and mortality rates by month of age in the population who was near the age of 70 years threshold. At age 70 years, the influenza vaccination rate increased by 29.1% (95% CI, 28.2% to 29.9%) compared to those under 70 in the study population. When turning age 70 years, the potential effectiveness of receiving influenza vaccine was 8.2% (95% CI, -36.8% to 51.3%) for total hospitalization and the evaluation of vaccine effectiveness was 13.1% (95% CI, -34.2 to 61.8) for the all-cause mortality. An increase in the influenza vaccination rate was associated with a weak decline in most outcomes, but no significance was found for all outcomes. Influenza vaccination had a limited effect on hospital admission and mortality for the free influenza vaccination program that can be related to the low vaccination rate among the Chinese elderly. Supplementation strategies and future studies may be needed to expand immunization coverage and validate this finding, and further provide a reference for other cities to promote the free influenza vaccination policy in China, especially under circumstances of the COVID-19 pandemic.

Factors associated with influenza vaccination coverage and willingness in the elderly with chronic diseases in Shenzhen, China

Elderly individuals with chronic illnesses are more prone to get influenza. We aimed to investigate the factors associated with influenza coverage and willingness in chronic disease patients aged ≥60 years in Longhua district, Shenzhen City of southern China. Data collected in October 2020 were used in this work. The immunization status of older persons with chronic conditions and their willingness to receive the vaccine were assessed. Multivariable logistic regression was employed to determine the respective independent factors related to vaccination coverage and willingness for influenza. Only 4.8% of 5045 people were immunized against influenza, whereas 92.7% of the individuals agreed to receive the vaccine. Individuals between the ages of 70 and 79 (adjusted OR [aOR] 1.47, P = .012), those with higher education levels (aOR 1.53, P = .005 for high school; aOR 2.44, P < .001 for college or above), those who use of a family doctor (aOR 2.91, P < .001), those who frequently have physical examinations once a year (aOR 2.52, P < .001), and those who have never smoked (aOR 1.62, P = .018) were positively associated with the influenza vaccination. Meanwhile, older age was adversely linked with influenza vaccination willingness (aOR 0.68 for 70-79 years, P = .003; aOR 0.55 for≥80 years, P = .025) in contrast to those aged 60-69. High willingness to get vaccinated was more frequent in people with a high school diploma (aOR 1.33, P = .037). In this work, we observed that the coverage is poor but the immunization desire is high regarding influenza vaccination. Interestingly, older age was associated with higher coverage and lower willingness. These suggest that raising immunization rates among older people with chronic conditions and strengthening health education for caregivers should be the primary concerns.

Drivers of and barriers to routine adult vaccination: A systematic literature review

We performed a systematic literature review in PubMed and Embase (2016-2021) to investigate the drivers of and barriers to routine vaccination in adults aged 50 and older globally. A thematic assessment identified three categories across 61 publications: sociodemographic, health-related, and attitudinal. The most common sociodemographic determinants (factors identified in studies; n = 47) associated with vaccination uptake were economic status, age, education, and household composition, which had mixed effects on vaccine uptake. For health-related determinants (n = 27), individuals with comorbidities and health care consumption were the most common factors, both increased vaccine uptake. The most common attitudinal factors (n = 42) were self-efficacy, provider or other's recommendations, and vaccine-preventable disease awareness; across studies, all attitude factors had a positive effect, unlike the sociodemographic and health status categories. Findings suggest that patient and provider awareness and education campaigns are effective ways to increase uptake of routine vaccinations in older adults.

Trends and factors associated with influenza vaccination in subjects with asthma: analysis of the Korea National Health and Nutrition Examination Survey between 2010 and 2019

BACKGROUND

Despite the importance of influenza vaccination, its rates in subjects with asthma are suboptimal, especially in the young population.

METHODS

Among 72,843 adults aged ⩾18 years from the Korea National Health and Nutrition Examination Survey conducted between 2010 and 2019, 1643 with asthma were included. The yearly trends and factors associated with influenza vaccination were analyzed in subjects with asthma. In addition, stratified analyses were performed by age group (<65 versus ⩾65 years).

RESULTS

During the study period, the overall influenza vaccination rate among subjects with asthma fluctuated from 51.0% to 64.3%, with a consistently higher vaccination rate in elderly subjects than in young subjects. Among young subjects with asthma, factors positively associated with influenza vaccination were female sex [adjusted odds ratio (aOR) = 1.66, 95% confidence interval (CI) = 1.11-2.49], current asthma being treated (aOR = 1.69, 95% CI = 1.14-2.50), history of pulmonary tuberculosis (aOR = 2.01, 95% CI = 1.04-3.87), and dyslipidemia (aOR = 1.86, 95% CI = 1.05-3.30). However, unmarried subjects showed an inverse relationship (aOR = 0.50, 95% CI = 0.34-0.75). In elderly subjects, unmarried status (aOR = 0.52, 95% CI = 0.29-0.94), being underweight (aOR = 0.29, 95% CI = 0.09-0.97), and having a low income (aOR = 0.42, 95% CI = 0.18-0.97) were factors negatively associated with influenza vaccination.

CONCLUSION

In the last 10 years, influenza vaccination rates have still been insufficient in subjects with asthma, particularly in young subjects. Considering the factors that are influencing the vaccination rates of young subjects, public policies to increase influenza vaccination rates in subjects with asthma need to be established urgently.

Severe mental disorders and vaccinations - a systematic review

OBJECTIVES

People with severe mental illnesses (SMI: schizophrenia, depressive disorder, bipolar disorder) have a high risk of being infected by viruses and suffer a more severe infection illness course than the general population. The aim of this literature review was to elucidate rates as well as immunogenicity and side effects of vaccinations in SMI.

METHODS

All studies in the English or German language, which investigated either prevalence rates or effects of vaccinations in the target groups, were systematically searched in the databank PubMed by three independent authors using the PRISMA guidelines and discussed in more detail.

RESULTS

The search found 24 studies reporting epidemiological data and 16 investigating immunogenicity of vaccinations. The results on prevalence rates, antibody production, inflammation response and side effects were inconsistent. About interactions with psychotropic medication, only two studies on clozapine were found.

CONCLUSIONS

Only a few trials with heterogeneous samples have investigated prevalence and effects of vaccinations in SMI. Sex, age and other factors such as somatic comorbidities and special vaccination programmes have not been considered continuously and may influence rates as well. As individuals with SMI might be at special risk, further research on the willingness to be vaccinated as well as efficacy of vaccinations is needed.

Willingness to be vaccinated against COVID-19 is equal in individuals with affective disorders and healthy controls

Affective disorders such as major depressive disorder and bipolar disorder are associated with higher infection rates and a more severe course of coronavirus disease (COVID-19). In turn, COVID-19 could trigger mental disease relapse. Vaccinations lead to a reduction of infections and the prevention of severe courses. This work aims to survey the willingness of individuals with affective disorders to get vaccinated and concerns about vaccinations.

METHODS

An online study (April-May 2021) assessed the current infection and vaccination rate amongst individuals with affective disorder in Austria by surveying attitudes towards the vaccination, the willingness to get vaccinated soon and possible reasons for decision. The analyses included 59 individuals with affective disorders and 59 healthy controls, matched for sex and age.

RESULTS

There was an overall high willingness to get vaccinated against COVID-19. Individuals with affective disorders were more skeptical about vaccinations in general but there was no significant difference between the groups in the willingness to get vaccinated against COVID-19. In both groups reasons for waiting were mainly fears of acute and/or long-term side effects and the fast development of the vaccines.

LIMITATIONS

It was a cross sectional design. Due to the online design, no objective rating of current psychopathological symptoms was assessed. Willingness to get vaccinated in general and against COVID-19 in particular were self-created variables, whereas item statistics and factor analysis were conducted.

DISCUSSION

Because of the higher risk for individuals with affective disorders, preventive strategies like vaccinating should be promoted in this group. It is important to help individuals with AD to overcome barriers such as negative beliefs and concerns about acute and/or long-term side effects.

Influenza vaccination hesitancy and its determinants among elderly in China: A national cross-sectional study

BACKGROUND

The Chinese elderly face a significant threat from seasonal influenza, owing to the consistently low vaccination coverage. This study investigated the prevalence and determinants of influenza vaccination hesitancy among the Chinese elderly.

METHODS

In 2019, 3849 elderly individuals from 10 provinces in China were recruited in a cross-sectional survey. Multinomial logistic regression was applied to investigate the determinants of influenza vaccination hesitancy.

RESULTS

Among the elderly respondents, 37.18% expressed some degree of hesitancy towards influenza vaccination: 19.28% were hesitant, and 17.90% refused influenza vaccination, including 19.28% acceptors with doubts and 17.90% refusers. Only 39.10% of the respondents considered themselves as the priority group for influenza vaccination, and 13.93% reported receiving a recommendation for vaccination from healthcare workers. Respondents with higher education levels and from urban areas had significantly higher odds of vaccine hesitancy than their counterparts. Confidence in the safety of vaccines was negatively associated with vaccine hesitancy, but confidence in vaccine efficacy had no such association. Respondents who perceived themselves as highly susceptible to influenza (AOR = 0.85; 95 %CI = 0.77-0.93) and those aware of the elderly as a priority group for influenza vaccination (AOR = 0.51; 95 %CI = 0.41-0.64) had a significantly lower odds of being refusers.

CONCLUSION

This study found a high prevalence of hesitancy towards influenza vaccination among the Chinese elderly, especially well-educated and urban-dwelling respondents. The government should address vaccine hesitancy through culturally appropriate communication, subsidies for vaccination, and actively promoting vaccines through primary care professionals.

Trends in Excess Winter Mortality (EWM) from 1900/01 to 2019/20-Evidence for a Complex System of Multiple Long-Term Trends

Trends in excess winter mortality (EWM) were investigated from the winter of 1900/01 to 2019/20. During the 1918–1919 Spanish flu epidemic a maximum EWM of 100% was observed in both Denmark and the USA, and 131% in Sweden. During the Spanish flu epidemic in the USA 70% of excess winter deaths were coded to influenza. EWM steadily declined from the Spanish flu peak to a minimum around the 1960s to 1980s. This decline was accompanied by a shift in deaths away from the winter and spring, and the EWM calculation shifted from a maximum around April to June in the early 1900s to around March since the late 1960s. EWM has a good correlation with the number of estimated influenza deaths, but in this context influenza pandemics after the Spanish flu only had an EWM equivalent to that for seasonal influenza. This was confirmed for a large sample of world countries for the three pandemics occurring after 1960. Using data from 1980 onward the effect of influenza vaccination on EWM were examined using a large international dataset. No effect of increasing influenza vaccination could be discerned; however, there are multiple competing forces influencing EWM which will obscure any underlying trend, e.g., increasing age at death, multimorbidity, dementia, polypharmacy, diabetes, and obesity—all of which either interfere with vaccine effectiveness or are risk factors for influenza death. After adjusting the trend in EWM in the USA influenza vaccination can be seen to be masking higher winter deaths among a high morbidity US population. Adjusting for the effect of increasing obesity counteracted some of the observed increase in EWM seen in the USA. Winter deaths are clearly the outcome of a complex system of competing long-term trends.

Outcomes associated with different vaccines in individuals with bipolar disorder and impact on the current COVID-19 pandemic- a systematic review

Bipolar disorder (BD) might be associated with higher infection rates of coronavirus disease (COVID-19) which in turn could result in worsening the clinical course and outcome. This may be due to a high prevalence of somatic comorbidities and an increased risk of delays in and poorer treatment of somatic disease in patients with severe mental illness in general. Vaccination is the most important public health intervention to tackle the ongoing pandemic. We undertook a systematic review regarding the data on vaccinations in individuals with BD. Proportion of prevalence rates, efficacy and specific side effects of vaccinations and in individuals with BD were searched. Results show that only five studies have investigated vaccinations in individuals with BD, which substantially limits the interpretation of overall findings. Studies on antibody production after vaccinations in BD are very limited and results are inconsistent. Also, the evidence-based science on side effects of vaccinations in individuals with BD so far is poor.

Influenza Vaccination Coverage among Older Adults with Hypertension in Shenzhen, China: A Cross-Sectional Survey during the COVID-19 Pandemic

Background: Older individuals with hypertension are at a high risk of being infected with influenza. However, there have been few studies investigating the influenza vaccination status among older people with hypertension. The present work aimed to estimate the vaccination coverage and determine the predictors of seasonal influenza vaccinations among hypertensive patients aged over 60 years in Shenzhen, China. Method: The study used data from an online cross-sectional survey that was conducted in Shenzhen City, China, in October 2020. Frequencies and proportions of all the variables including sociodemographic characteristics and health-related information were described and tabulated based on the influenza vaccination status. Bivariate and multivariable logistic regression analyses were used to identify independent predictors associated with the influenza vaccination. Results: A total of 5216 older people with hypertension aged above 60 years were recruited. Overall, only 4.7% had received an influenza vaccine in the latest influenza season. Using the action toward being vaccinated as the primary outcome, the multivariable regression analysis showed that participants aged over 80 years (aOR 2.957, 95% CI: 1.784–4.900), obtaining higher education levels (aOR 1.424, 95% CI: 1.060–1.914 for high school, aOR 1.681, 95% CI: 1.066–2.650 for college or above), living with a partner (aOR 1.432, 95% CI: 1.068–1.920), using a family doctor (aOR 2.275, 95% CI: 1.744–2.968), and taking a physical examination 1–2 and ≥3 times each year (aOR 2.107, 95% CI: 1.601–2.772 and aOR 2.118, 95% CI: 1.083–4.143, respectively) were more likely to be vaccinated. In contrast, smokers had less likelihood of having the influenza vaccination than non-smokers (aOR 1.829, 95% CI: 1.208–2.767). Conclusions: The coverage rate of influenza vaccinations is far away from optimistic among older adults with hypertension. Additional works should be undertaken immediately to improve the influenza vaccination status.

The role of health determinants in the influenza vaccination uptake among older adults (65+): a scope review

Background

Although the burden of influenza infection is the highest in older adults, vaccination coverage remains low, despite this age group being more vulnerable than others.

Aims

Given the current pandemic of SARS-CoV-2, it was the aim of this scope review to update knowledge on factors affecting seasonal influenza vaccine uptake among older adults to strengthen prevention approaches in the context of an overall burden of infectious diseases.

Methods

We searched bibliographic databases from 2012 to 2019. All studies reviewed one or more social determinant of health listed by WHO, or factors affecting the decision-making process whether to accept influenza vaccine or not.

Results

Overall, 44 studies were included, 41 determinants were extracted and summarized into six categories. Older age and constitutional factors including multiple chronic diseases as well as preventive lifestyle and frequent routine healthcare utilization positively affected vaccination uptake (VU). Living and working conditions are also researched determinants of influenza vaccine uptake. A small number of studies explored the role of social inclusion and system-based interventions.

Discussion and conclusions

This scope review provides a comprehensive overview on factors affecting seasonal influenza vaccination uptake among older citizens. The review also clearly shows gaps for evidence on system-based level or political strategies to improve vaccination uptake.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40520-021-01793-3.

Factors associated with influenza vaccine coverage among patients with diabetes: Korea National Health and Nutrition Examination Survey 2016-2018

Background

Although the influenza vaccine has been proven to be effective, this common disease has high morbidity and mortality rates. Moreover, adults with diabetes are at a high risk of influenza-mediated morbidity and mortality.

Purpose of the study

With the increasing prevalence of diabetes, influenza is more lethal in diabetics; thus, we aimed to investigate the factors associated with influenza vaccination coverage in patients with diabetes.

Methods

Cross-sectional data were obtained from the Korea National Health and Nutrition Examination Survey (2016–2018). We retrospectively analyzed whether sociodemographic, health-related, and medical factors are associated with influenza vaccination coverage in patients with diabetes. We performed a complex sample logistic regression analysis and estimated the odds ratios (ORs) by adjusting for statistically significant factors.

Results

The number of survey subjects was 18,553. The vaccine coverage rate among patients with diabetes was 60.6%. In the univariate analysis, sex, educational level, smoking, exercise, drinking, marital status, private health insurance, activity limit, economic activity, age, and EuroQol-5 Dimension scores, which were used to assess health-related quality of life, were associated with vaccination coverage. In the multivariate analysis, only age and economic activity were associated with vaccination coverage. The vaccination coverage rate was higher for people who did not undertake economic activities and who were older (OR 1.512 (1.087–2.105), OR 2.212 (1.822–2.686), respectively, p < 0.001).

Conclusion

National interventions involving public health centers are necessary to encourage influenza immunization for patients with diabetes, especially younger patients and those who work or undertake economic activities.

Influenza Vaccination Status and Its Affecting Factors among Stroke Survivors: Findings from the Korea National Health and Nutrition Examination Survey

Few studies have examined the influenza vaccination rates among stroke survivors despite the importance of vaccines in preventing influenza- and stroke-related complications. Thus, we investigated the vaccination rates and the associated factors among stroke survivors using the representative Korea National Health and Nutrition Examination Survey 2014–2018. We measured and compared the vaccination rates of 591 stroke survivors and 17,997 non-stroke survivors. Multivariate logistic regression analyses of all stroke survivors and age subgroups (<65 and ≥65 years) were performed to identify the factors influencing vaccination. The overall vaccination rate was significantly higher in the stroke survivors (64.8%) than in the non-stroke survivors (41.1%), but it was low compared to global standards. Among stroke survivors aged <65 years, the rate was low (37.5%), but it improved in those aged ≥65 years (85.6%). Age ≥ 65 years, the eligible age for the national free vaccination program was the most prominent predictor of vaccination for all stroke survivors, while smoking was a negative predictor. No significant factors were found in the subgroup analyses according to age (<65 and ≥65 years). Therefore, implementing strategic public health policies, such as expanding the free vaccination program to stroke survivors aged <65 years, may improve vaccine coverage.

Achieving Influenza Vaccine Uptake Target in Canada via a Pharmacy-Led Telephone Discussion during the 2019-2020 Season

Older adults (≥65 years) are at elevated risk of influenza-related morbidity and mortality. Many developed countries do not achieve the World Health Organization influenza immunization target of 75% in people ≥65 years. We aimed to determine whether a brief pharmacy phone call could increase vaccine uptake of standard and enhanced influenza. Twenty-eight community pharmacists across Canada performed a telephone consultation with 643 older adults whose primary care records indicated that they had not received their influenza vaccination from their usual practitioner. Of these 643 adults, 169 (26.3%) had been vaccinated in another setting. Of the remaining 474, 313 (66%) agreed to receive the vaccine. Of those who refused vaccination, 69 provided a rationale for not wanting it, including that the flu shot "causes the flu" (n = 25), "doesn't work" (n = 25), "is too painful" (n = 10), and other (n = 10). Overall, of the 643 individuals who had not received their vaccination from their usual health care provider in the first wave of vaccinations, 75.4% (n = 485) ultimately received their vaccination in the 2019-2020 season. This highlights the important role of the community pharmacist in achieving the World Health Organization (WHO) targets for vaccination.

Machine learning models to identify low adherence to influenza vaccination among Korean adults with cardiovascular disease

Background

Annual influenza vaccination is an important public health measure to prevent influenza infections and is strongly recommended for cardiovascular disease (CVD) patients, especially in the current coronavirus disease 2019 (COVID-19) pandemic. The aim of this study is to develop a machine learning model to identify Korean adult CVD patients with low adherence to influenza vaccination

Methods

Adults with CVD (n = 815) from a nationally representative dataset of the Fifth Korea National Health and Nutrition Examination Survey (KNHANES V) were analyzed. Among these adults, 500 (61.4%) had answered "yes" to whether they had received seasonal influenza vaccinations in the past 12 months. The classification process was performed using the logistic regression (LR), random forest (RF), support vector machine (SVM), and extreme gradient boosting (XGB) machine learning techniques. Because the Ministry of Health and Welfare in Korea offers free influenza immunization for the elderly, separate models were developed for the < 65 and ≥ 65 age groups.

Results

The accuracy of machine learning models using 16 variables as predictors of low influenza vaccination adherence was compared; for the ≥ 65 age group, XGB (84.7%) and RF (84.7%) have the best accuracies, followed by LR (82.7%) and SVM (77.6%). For the < 65 age group, SVM has the best accuracy (68.4%), followed by RF (64.9%), LR (63.2%), and XGB (61.4%).

Conclusions

The machine leaning models show comparable performance in classifying adult CVD patients with low adherence to influenza vaccination.

Impacts of free vaccination policy and associated factors on influenza vaccination behavior of the elderly in China: A quasi-experimental study

BACKGROUND

Chinese elders are under high threats of seasonal influenza, while showing low influenza vaccination coverage comparing with other countries. The study explored the impacts of free vaccination policy and associated factors on influenza vaccination behavior of the elderly in Zhejiang Province, China, offering a guidance of interventions for protecting elders from seasonal influenza.

METHODS

1210 elders ≥60 years were conveniently recruited between July and September of 2019. 607 of them were sampled from 6 counties with free vaccination policy, while the other 603 elderly people were sampled from another 6 comparable counties without the policy. A self-reported questionnaire, involving socio-democratic information, physical status and behavior, influenza knowledge, vaccination awareness, relatives of healthcare workers, and vaccination behavior, was completed by elders under supports of research assistants. Chi-square tests and logistic regression analyses were performed to explore the impacts of research factors.

RESULTS

A total of 464 (38.3%, 95%CI: 36.9-39.7%) elders claimed that they got vaccinated, and the vaccination coverages of elders in the counties with and without free vaccination policy were 68.4% (95%CI: 64.7-72.1%) and 8.1% (95%CI: 5.9-10.3%), respectively. Protective and risk factors of vaccination behavior were identified, including free vaccination policy (OR_step = 27.29, 95%CI: 18.69-39.82), positive vaccination awareness (OR_step = 7.93, 95%CI: 5.50-11.43), catching cold frequently (OR_step = 2.00, 95%CI: 1.32-3.05), and having relatives of healthcare workers (OR_step = 0.56, 95%CI: 0.34-0.93). Age, education level, monthly income, family structure, physical status, and influenza knowledge were significantly associated with vaccination behavior. Having relatives of healthcare workers may indirectly affect vaccination behavior through vaccination awareness.

CONCLUSIONS

Free vaccination policy plays the most fundamental role of improving vaccination coverage among studied factors. To protect elders from seasonal influenza, effective measurements, such as issuing free vaccination policy, enriching influenza knowledge, and guiding positive vaccination awareness for both elders and healthcare professionals are recommended to be included into influenza immunization strategies.

Trends, Coverage and Influencing Determinants of Influenza Vaccination in the Elderly: A Population-Based National Survey in Spain (2006-2017)

Influenza is a significant public health problem and the elderly are at a greater risk of contracting the disease. The vaccination coverage of the elderly is below the Spanish target of 65% for each influenza season. The aims of this study were to report the coverage of influenza vaccination in Spain among the population aged ≥65 years and high-risk groups for suffering chronic diseases, to analyze the time trends from 2006 to 2017 and to identify the factors which affect vaccination coverage. A nationwide cross-sectional study was conducted including 20,753 non-institutionalized individuals aged ≥65 years who had participated in the Spanish National Health Surveys in 2006, 2011/2012, and 2017. Sociodemographic, health-related variables, and influenza vaccination data were used. A logistic regression analysis was performed to determine the variables associated with influenza vaccination. Influenza vaccination coverage was 60%. By chronic condition, older people with high cholesterol levels and cancer had the lowest vaccination coverage (62.41% and 60.73%, respectively). This coverage declined from 2006 to 2017 in both groups. Higher influenza vaccination was associated with males, Spanish nationality, normal social support perceived, polypharmacy, worse perceived health, participation in other preventive measures, and increasing age and the number of chronic diseases.

Seasonal influenza vaccination in older people: A systematic review and meta-analysis of the determining factors

Background/Objectives

Despite influenza vaccination programs in various jurisdictions, seasonal influenza vaccine (SIV) uptake remains suboptimal among older people (≥65years old), an important subpopulation for influenza vaccination. We sought to summarize determinants of SIV uptake (any vaccine receipt) and vaccination adherence (receipt of vaccine in two or more seasons in sequence) among older people.

Methods

We searched for population-based studies conducted in community-dwelling older people (irrespective of their health status) from 2000–2019. Two reviewers independently selected publications for inclusion. One reviewer extracted data from the included studies; a second checked the extracted data for errors. Disagreements were resolved by discussion and consensus, or a third reviewer. We were interested in the determinants of SIV uptake and vaccination adherence. Where appropriate, we pooled adjusted results using the inverse variance, random-effects method and reported the odds ratios (OR) and their 95% confidence intervals (CI).

Results

Out of 11,570 citations screened, we included 34 cross-sectional studies. The following were associated with increased SIV uptake: being older (OR 1.52, 95%CI 1.38–1.67 [21 studies]), white (1.30, 1.14–1.49 [10 studies]), married (1.23, 1.17–1.28 [9 studies]), non-smoker (1.28, 1.11–1.47 [7 studies]), of a higher social class (1.20, 1.06–1.36 [2 studies]), having a higher education (1.12, 1.04–1.21 [14 studies]), having a higher household income (1.11, 1.05–1.18 [8 studies]), having a chronic illness (1.53, 1.44–1.63 [16 studies]), having poor self-assessed health (1.23, 1.02–1.40 [9 studies]), having a family doctor (2.94, 1.79–4.76 [2 studies]), and having health insurance (1.58, 1.13–2.21 [6 studies]). The influence of these factors varied across geographical regions. Being older (1.26, 1.11–1.44 [2 studies]) was also associated with increased vaccination adherence.

Conclusions

Several factors may determine SIV uptake and vaccination adherence among older people. More studies are needed to provide a stronger evidence base for planning more effective influenza vaccination programs.

Prevalence and associated factors of influenza vaccination coverage in Korean adults with cardiovascular disease

Infection with influenza virus increases morbidity and mortality in patients with risk factors, including cardiovascular disease (CVD). This study aimed to evaluate factors associated with influenza vaccination coverage in Korean CVD patients.We included 19,599 adults from the 2010 to 2012 Korea National Health and Nutrition Examination Survey. Influenza vaccination rates were compared in subjects with and without CVD. Logistic regression analysis was performed to identify factors associated with influenza vaccination in Korean adults with CVD before and after stratification for age (<65 and ≥65 years).Significantly higher vaccination rates were observed in individuals with CVD than in those without CVD (61.4% vs 31.0%, P < .001). However, young individuals (19-49 years) had decreased influenza vaccination rates, with no difference based on CVD status (20.3% vs 21.6%, P = .859). A lack of private insurance (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.23-0.98) and recent health screening (OR, 4.56; 95% CI, 1.90-10.92) were independent factors for influenza vaccination in CVD patients aged <65 years, whereas female sex (OR, 3.71; 95% CI, 1.24-11.07) and less education (OR, 4.59; 95% CI, 1.27-16.61) were independent factors in CVD patients aged ≥65 years.Improving influenza vaccination coverage for Korean adults with CVD is important, especially in young patients. For young patients with CVD, influenza vaccination status is independently associated with the presence of private insurance and recent health screening. This finding could help establish public health policies to promote influenza vaccination in this population.

Increasing Influenza and Pneumococcal Vaccination Uptake in Seniors Using Point-of-Care Informational Interventions in Primary Care in Singapore: A Pragmatic, Cluster-Randomized Crossover Trial

Objectives. To evaluate the effectiveness of point-of-care informational interventions in general practitioner clinics to improve influenza and pneumococcal vaccination uptake among elderly patients.Methods. We conducted a pragmatic, cluster-randomized crossover trial in 22 private general practitioner clinics in Singapore, from November 2017 to July 2018. We included all patients aged 65 years or older. Clinics were assigned to a 3-month intervention (flyers and posters encouraging vaccination) plus 1-month washout period, and a 4-month control period (usual care). Primary outcomes were differences in vaccination uptake rates between periods. Secondary outcomes were identification of other factors associated with vaccination uptake.Results. A total of 4378 and 4459 patients were included in the intervention and control periods, respectively. Both influenza (5.9% vs 4.8%; P = .047) and pneumococcal (5.7% vs 3.7%; P = .001) vaccination uptake rates were higher during the intervention period compared with the control period. On multilevel logistic regression analysis, follow-up for hypertension, diabetes mellitus, hyperlipidemia, or any combination of the 3 was associated with uptake of both vaccines.Conclusions. Point-of-care informational interventions likely contributed to increased influenza and pneumococcal vaccination uptake. Patients on follow-up for hypertension, diabetes mellitus, hyperlipidemia, or any combination of the 3 were more likely to receive influenza and pneumococcal vaccination and should be actively engaged by physicians.Trial Registration. ClinicalTrials.gov Identifier: NCT03445117.

Short-term effects of multiple outdoor environmental factors on risk of asthma exacerbations: Age-stratified time-series analysis

BACKGROUND

Although the different age groups had differences in sensitivity of asthma exacerbations (AEs) to environmental factors, no comprehensive study has examined the age-stratified effects of environmental factors on AEs.

OBJECTIVE

We sought to examine the short-term effects in age-stratified groups (infants, preschool children, school-aged children, adults, and the elderly) of outdoor environmental factors (air pollutants, weather conditions, aeroallergens, and respiratory viral epidemics) on AEs.

METHODS

We performed an age-stratified analysis of the short-term effects of 4 groups of outdoor environmental factors on AEs in Seoul Metropolitan City (Korea) from 2008 and 2012. The statistical analysis used a Poisson generalized linear regression model, with a distributed lag nonlinear model for identification of lagged and nonlinear effects and convergent cross-mapping for identification of causal associations.

RESULTS

Analysis of the total population (n = 10,233,519) indicated there were 28,824 AE events requiring admission to an emergency department during the study period. Diurnal temperature range had significant effects in pediatric (infants, preschool children, and school-aged children) and elderly (relative risk [RR], 1.056-1.078 and 1.016, respectively) subjects. Tree and weed pollen, human rhinovirus, and influenza virus had significant effects in school-aged children (RR, 1.014, 1.040, 1.042, and 1.038, respectively). Tree pollen and influenza virus had significant effects in adults (RR, 1.026 and 1.044, respectively). Outdoor air pollutants (particulate matter of ≤10 μm in diameter, nitrogen dioxide, ozone, carbon monoxide, and sulfur dioxide) had significant short-term effects in all age groups (except for carbon monoxide and sulfur dioxide in infants).

CONCLUSION

These findings provide a need for the development of tailored strategies to prevent AE events in different age groups.

The association between influenza vaccination and socioeconomic status in high income countries varies by the measure used: a systematic review

Background

The purpose of this paper is to systematically review the literature on the relationship between socioeconomic status (SES) and influenza immunization and to examine how certain measures of SES may influence interpretations of this relationship.

Methods

We conducted a systematic review of existing peer-reviewed literature to evaluate the above relationship in the general population. Electronic databases (MEDLINE and EMBASE) were searched from January 2012 to May 2017 to identify English-language studies relevant to this review. Studies were included where influenza vaccination was explicitly reported as the dependent variable and SES as the independent variable. We limited our review to measures of SES that focus on education, income, social class, occupation, and deprivation. Studies that measured SES using other variables (e.g., race, ethnicity, geographic location, rural or urban status, or insurance status) were excluded. Studies were also excluded if they did not report on the human population or did not analyze original data. The population of interest included all age groups, levels of health status, and sociodemographic backgrounds. The review was also limited to World Bank high-income countries. Two authors independently screened full-text articles after obtaining a Kappa score of K = 0.867. The methodological quality of manuscripts was assessed using the appraisal tools developed by the Joanna Briggs Institute. Results were qualitatively reported and synthesized.

Results

Of the 42 articles included in this review, 52.4% (n = 22) found that higher levels of SES resulted in higher levels of influenza vaccination; 4.5% (n = 2) reported a negative association; and 14.3% (n = 6) found no association. Just over a quarter (26.2%, n = 12) of articles reported mixed results.

Conclusions

There was consistently a relationship between SES and influenza immunization, which varied according to how SES was measured. It is recommended that authors be explicit in defining the SES concept they are trying to capture and that they utilize multiple measures of SES (e.g., education, income, class).

Electronic supplementary material

The online version of this article (10.1186/s12874-019-0801-1) contains supplementary material, which is available to authorized users.

The coverage rates for influenza vaccination and related factors in Korean adults aged 50 and older with chronic disease: based on 2016 Community Health Survey data

OBJECTIVES

This study aims to identify the coverage rates for influenza vaccination and related factors depending on chronic disease in Korean adults aged 50 and older.

METHODS

The 2016 Korea Community Health Survey was used for analysis. Chi-square test was performed to investigate the coverage rates for influenza vaccination depending on chronic disease, and a multiple logistic regression analysis was used to identify the factors associated with influenza vaccination, by chronic disease.

RESULTS

In men with ≥1 chronic disease, 39.8% of 50-64 years of age, and 86.8% of elderly (over 65 years of age) received influenza vaccination. In women with ≥1 chronic disease, 58.7% of 50-64 years of age, and 89.9% of elderly (over 65 years of age) received influenza vaccination (p<0.001). The chronic diseases associated with influenza vaccination were hypertension (odds ratio [OR], 1.27; 95% confidence interval [CI], 1.19 to 1.37), diabetes (OR, 1.41; 95% CI, 1.28 to 1.55) in men aged 50-64, hypertension (OR, 1.34; 95% CI, 1.20 to 1.49), diabetes (OR, 1.17; 95% CI, 1.02 to 1.33), chronic cardiovascular disease (OR, 1.31; 95% CI, 1.07 to 1.60) in elderly (over 65 years of age). In women aged 50-64, hypertension (OR, 1.39; 95% CI, 1.30 to 1.49), diabetes (OR, 1.51; 95% CI, 1.35 to 1.68), chronic cardiovascular disease (OR, 1.31; 95% CI, 1.05 to 1.64), and hypertension (OR, 1.55; 95% CI, 1.40 to 1.71), diabetes (OR, 1.27; 95% CI, 1.12 to 1.43) in elderly (over 65 years of age).

CONCLUSIONS

Populations in aged 50-64 are recommendation subject for vaccination or classified as high-risk group in case with chronic disease. Though subject over 60 years old is age close to the elderly, the coverage rates for vaccination was low. It is necessary to devise strategies to raise the coverage rates for vaccination.

Influenza vaccination in the elderly

Seasonal influenza is a prevalent and serious annual illness resulting in widespread morbidity and economic disruption throughout the population; the elderly and immunocompromised are particularly vulnerable to serious sequelae and mortality. The changing demographics worldwide to an aging society have important implications for public health policy and pharmaceutical innovations. For instance, primary prevention via immunization is effective in reducing the burden of influenza illness among the elderly. However, the elderly may be insufficiently protected by vaccination due to the immunosenescence which accompanies aging. In addition, vaccine hesitancy among the younger populations increases the likelihood of circulating infectious diseases, and thus concomitant exposure. While it is clear that the development of more immunogenic vaccines is an imperative and worthy endeavor, clinical trials continue to demonstrate that the current influenza vaccine formulation remains highly effective in reducing morbidity and mortality when well matched to circulating strains.

Factors influencing on influenza vaccination and its trends of coverage in patients with diabetes in Korea: A population-based cross-sectional study

BACKGROUND

Influenza infection is a contagious disease and annual influenza vaccination is recommended to the patients with chronic diseases. Although diabetes is an indication for influenza vaccination, the global rate of influenza vaccination is insufficient. Therefore, our study aimed to elucidate influenza vaccination statuses among patients with diabetes and the related factors in Korea.

METHODS

A total of 32,268 subjects (4,540 with and 27,728 without diabetes) from the Korea National Health and Nutrition Examination Survey III-VI (2005-2015) were included. Socioeconomic factors and health-related factors were analyses for the relation of influenza vaccination by Student's t-test, the chi-squared test and a multivariate logistic regression analysis.

RESULTS

The influenza vaccination coverage rates were 50.0% in the diabetes mellitus (DM) group and 38.2% in the non-DM group. The trends in influenza vaccination rates during KNHANES III-VI were not significant in each group (P trend  =  0.24 in the DM group, 0.30 in the non-DM group). Socioeconomic (older age, female sex, higher family income, and medical aid insurance) and health-related factors (lack of risky alcohol consumption, obesity, and recent health check-ups) were associated with influenza vaccination among patients with DM.

CONCLUSIONS

The rate of influenza vaccination among patients with diabetes is insufficient in Korea. More efforts are needed to increase the influenza vaccination rates among vulnerable at-risk populations.

Lifestyle, socioeconomic characteristics, and medical history of elderly persons who receive seasonal influenza vaccination in a tax-supported healthcare system

BACKGROUND

Observational studies on effectiveness of influenza vaccination in the elderly are thought to be biased by healthier lifestyles and higher socioeconomic status among vaccinated vs. unvaccinated persons. We examined this hypothesis in a uniform tax-supported health care system with free-of-charge influenza vaccination to the elderly.

METHODS

We conducted a cross-sectional study among Danes aged 65-79years participating in a survey. We compared elderly persons with and without a recent (within six months) influenza vaccination in terms of (i) lifestyle and socioeconomic characteristics obtained from the survey and (ii) health factors including medical history provided by Danish registries. We compared the prevalence of study variables among vaccinated and unvaccinated persons using age- and sex-adjusted prevalence ratios (aPRs) with 95% confidence intervals (CIs).

RESULTS

Among the 4237 elderly persons completing the survey, 1718 (41%) had received an influenza vaccination. Vaccinated persons had more comorbidity than unvaccinated persons (aPR for high comorbidity level: 1.51 95% CI 1.24-1.84), were less likely to never have smoked (aPR: 0.88, 95% CI 0.80-0.97), and had a higher prevalence of physical inactivity (aPR: 1.08, 95% CI 1.03-1.13). Levels of education and income were similar in the two groups. Vaccinated persons had a higher prevalence of major physical limitations (aPR: 1.40, 95% CI 1.17-1.66) and need for assistance with activities of daily living (aPR: 1.29, 95% CI 1.13-1.47).

CONCLUSION

Elderly influenza vaccinated persons were not healthier in terms of lifestyle and burden of disease, did not have a higher socioeconomic status, and were more frail than unvaccinated persons.