Evolution of influenza vaccination coverage in France from 2001 to 2006

INTRODUCTION: The increased risk of a new influenza pandemic has raised awareness of the need for high influenza vaccination rates. OBJECTIVES: This study aims at assessing trends in influenza vaccination coverage from 2001 to 2006 in France, at understanding the drivers and barriers, and to identify vaccination intentions for 2006/2007. METHODS: We conducted a mail-based household survey on 9,835 persons representative of the population from age 15. Essentially, the same questionnaire was used in all seasons. RESULTS: The influenza vaccination coverage rate slightly increased, reaching 24.2% in 2005/2006 (70.1% in patients over 65). In the last two seasons the fact that the vaccination was provided for free was the most frequent reason for getting vaccinated. Older age, considering influenza as a serious disease and recommendations from the family doctor or nurse were also important drivers for vaccination. Only 2% of those vaccinated in 2005/2006 indicated the threat of avian influenza as a reason. The reasons for non-vaccination among persons never vaccinated before were feeling too young for vaccination, never having considered vaccination before and absence of recommendation by the family doctor. Among those who were previously vaccinated but not in the current season, the reasons for not being vaccinated were not finding vaccination necessary, forgetfulness and having influenza-like illness despite vaccination. CONCLUSION: Stable vaccination rates were observed from 2001 to 2006. France is well on its way to reach the international vaccination goal set by the WHO (75% in the elderly population), but continuously effort is needed for others.     

Effectiveness of the influenza vaccination program for the elderly in Taiwan

Background and objectives

Since 1998, an influenza vaccination program has been implemented by the Taiwan government targeting people aged ≥65 years. However, the evidence of the effectiveness of this program in preventing influenza, which is based on the nation-wide database, is lacking. This study attempted to estimate the effectiveness of the influenza vaccination program in preventing influenza- and pneumonia-associated outpatient visits and hospitalization in the elderly.

Methods

Randomly sampled data of 1 million claims from the National Health Insurance Research Database compiled into seven consecutive cohorts were used to perform this analysis. Elderly claimants aged ≥65 years were included in each cohort. To decrease potential bias between vaccinated and unvaccinated subjects, the propensity score method was applied. Logistic regression and zero-inflated negative binominal regression were used to examine the effectiveness of vaccination in preventing influenza- and pneumonia-associated outpatient visits and hospitalization.

Results

A significant decrease in both the risk and frequency of hospitalization was observed in elderly people who received influenza vaccination compared with those who did not. No similar decrease was observed in the risk and frequency of outpatient visits for influenza and pneumonia.

Conclusion

Vaccination against influenza reduced hospitalization for influenza and pneumonia in elderly Taiwanese people. These results are meaningful for the promotion of vaccination policy. Annual influenza vaccination of the elderly should be encouraged.     

基于倾向得分匹配的老年人接种流感疫苗对流感就诊的保护效果研究

目的 评估老年人接种流感疫苗对流感就诊的保护效果,并探讨倾向得分匹配法（PSM）在疫苗保护效果研究中的应用价值。方法 以成都市为研究现场,选取2017年9-12月间接种流感疫苗的60岁及以上老年人作为接种组,采用PSM法选取观察对象作为对照组。匹配后比较两组人群疫苗接种后一年内的流感就诊情况,评价疫苗保护效果。结果 流感疫苗接种组与未接种组各有1442例匹配成功。两组的一般人口学特征、生活方式及健康意识、基本健康状况等特征在匹配前有显著差异,匹配后两组协变量达到均衡。匹配后接种组和对照组流感就诊率分别为0.69%、2.84%,疫苗接种可减少之后一年内75.70%的流感就诊。结论 PSM可有效降低观察性研究组间的混杂偏倚,在疫苗接种效果评价中具有长远的应用价值。流感疫苗接种对降低≥60岁老年人流感就诊具有良好效果,今后有必要采取措施提高流感疫苗接种率。     

Developments in influenza vaccination coverage in England, Scotland and Wales covering five consecutive seasons from 2001 to 2006

This study aims at assessing trends in influenza vaccination coverage from 2001 to 2006 in Great Britain, at understanding drivers and barriers to vaccination and at identifying vaccination intentions for influenza season 2006/2007. In seasons 2001/2002 to 2005/2006, telephone-based household surveys representative of the population from age 16 were conducted, with about 2000 interviews per season (10,095 in total). Overall influenza vaccination coverage rate in Great Britain reached 25.9% in season 2005/2006. A sub-analysis showed that the highest coverage was reported in Wales reaching 33.3%. In the elderly recommended vaccination (from age 65), the coverage reached 79% in 2005/2006. Advice from the family doctor and the perception that influenza is a serious illness were the most frequent reasons for getting vaccinated. The most frequent reasons for not getting vaccinated, in persons never vaccinated before, were that they had not considered immunisation or had not received a recommendation from their family doctor. Those vaccinated in the past but not in the current season said they had not thought about vaccination/forgot. A gap continues to exist between those with intention to get vaccinated and those actually vaccinated, indicating a potential to increase vaccination coverage rate in the future. Our study shows that stable vaccination coverage rates were observed from 2002 to 2006 in Great Britain. The coverage had increased in Wales and in Scotland. The coverage among the elderly above 65 years was the highest in Europe. Although Great Britain complies with national and international goals of vaccination coverage rates effort is needed to ensure high vaccination coverage rates at the same level in the future.     

In a prospective observational study, influenza vaccination prevented hospitalization among older home care patients

OBJECTIVE: The aim of the study is (1) to describe the prevalence of vaccination against influenza in older home care patients and (2) to investigate the protective effect of influenza vaccination for hospitalization events. STUDY DESIGN AND SETTING: This is an observational study conducted in four large cohorts of elderly patients in home care during the 1998-1999, 1999-2000, 2000-2001, and 2001-2002 influenza seasons. We analyzed data from the Italian Silver Network Home Care project. A total of 2,201 patients were enrolled in the present study. The main outcome measures were prevalence of vaccination against influenza and the rate of hospitalization according to vaccination status and influenza season. RESULTS: The rate of influenza vaccination was around 48% of the studied sample. During the follow-up including the peak of influenza and the total influenza season, 412 subjects (40%) were hospitalized among vaccinated compared to 610 subjects (59%) among not vaccinated (P<0.001). After adjusting for age, gender, location of home care program, and all the variables significantly different between vaccinated and not-vaccinated subjects, vaccinated subjects were less likely to be hospitalized compared to not-vaccinated subjects (OR, 0.73; 95% CI 0.60-0.90). CONCLUSIONS: Vaccination against influenza has an important prognostic implication for frail geriatric patients living in the community.     

Compliance with influenza and pneumococcal vaccinations in Israel, 1999-2002

BACKGROUND: In a previous study, we found a relatively low compliance with influenza vaccination among the elderly (65 years and over) in both 1998/1999 and 1999/2000 winters. Prior to the 2000/2001 winter season, a campaign was conducted by the Israeli Ministry of Health and the local health maintanance organizations for improving compliance with influenza and pneumococcal vaccinations. The main purpose of the present study was to monitor the impact of that campaign on compliance with influenza and pneumococcal vaccinations. OBJECTIVES: (a) To compare the compliance rate of target groups with influenza vaccination in Israel during 2000/2001 and 2001/2002 winter seasons with previous years, (b) to estimate the compliance rate of the elderly with pneumococcal vaccination in Israel in the last 5 years, (c) to determine reasons for non-compliance. METHODS: Questions about compliance with influenza and pneumococcal vaccinations were included in quarterly national telephone surveys monitoring acute morbidity in Israel. Each survey was based on a sample of about 900 households and was carried out during three successive evenings. Questions were directed at interviewees of 18 years and over who were asked to report the vaccnation status of all the household members. RESULTS: A gradual increase in compliance with influenza vaccination was demonstrated for the elderly (aged 65 years and over) in the 2000/2001 (54.4%) and 2001/2002 (60.8%) winter seasons compared to the previous two seasons (51.6% in 1998/1999 and 49.1% in 1999/2000). A slight nonsignificant increase was also observed in the 50-64 age group (18.3% in 2002 survey). The proportion of the elderly who were reported to be vaccinated against pneumonia in the five years preceding the interview was higher in the 2002 survey (27.9%) compared to that of 2001 (20.1%). Lack of physician recommendation and low degreee of risk perception seem to be the major reasons hindering the achievement of higher rates of vaccination coverage. CONCLUSION: The vaccination campaign carried out in Israel prior to the 2000/2001 winter season was moderately successful in increasing the coverage of influenza and pneumococcal vaccinations in target groups. Performing this type of campaign every year before the influenza season should contribute to improving the compliance with vaccination of target groups.     

Coverage rates of influenza vaccination in France: a population-based cross-sectional analysis of seasons 2001-2002 and 2002-2003

INTRODUCTION: Influenza is a serious health problem in Europe. Vaccination is the only preventive measure, reducing mortality and morbidity of influenza in all age groups. OBJECTIVES: The authors had for aim to assess influenza vaccination coverage during two seasons in France, to understand the incentives and barriers to vaccination and to determine vaccination intentions for the following winter. METHODS: A random-sampling, mail-based household survey was made among non-institutionalised individuals aged 15 and over. The surveys for 2001-2002 and 2002-2003 used the same questionnaire and were subsequently pooled. Three target groups were determined for analysis: (1) persons aged 65 and over; (2) people working in the medical field and (3) persons aged 65 and over or working in the medical field. RESULTS: Influenza vaccination coverage in France decreased from 23.0% in 2001-2002 to 22.4% in 2002-2003. Most frequent reasons for being vaccinated were advice from the family doctor (50.8%), influenza considered as a serious illness (45.3%) and free vaccine (44.1%). Reasons for not being vaccinated mentioned by people who had never been vaccinated were young age (27.0%), not considering vaccination (18.9%), and not expecting to catch influenza (13.9%). CONCLUSION: Vaccination coverage decreased during the 2002-2003 season in comparison to the 2001-2002 season. The family doctor is the most important source of encouragement for people to be vaccinated against influenza. We therefore suggest that family doctors be better informed on influenza vaccine and the disease itself, so that they can actively inform their patients on these topics.     

Impact of repeated influenza vaccinations in persons over 65 years of age: A large population-based cohort study of severe influenza over six consecutive seasons, 2011/12–2016/17

BackgroundA forty-year debate on the potential negative effects of repeated seasonal influenza vaccination has been inconclusive, with multiple observational studies of various design providing heterogeneous results too inadequate to inform vaccination policy.MethodsA large population-based cohort study including over one-million observations in individuals over age 65 from six consecutive seasons (2011/12–2016/17) in Stockholm County, Sweden. Current season vaccine effectiveness (VE) against severe, mostly hospital-attended, influenza was assessed using Cox multivariate regression analyses adjusting for demographic variables, comorbidities and previous seasonal influenza vaccination status.ResultsIn none of the six seasons was VE significantly different in persons vaccinated in the current season only, compared to those who had been vaccinated in both the current and the previous season. Neither were there any differences in VE during the seasons 2014/15–2016/17 when comparing persons vaccinated during the current season only vs. those vaccinated during one-three or four-five previous influenza seasons. In contrast, persons only vaccinated during one or more previous years had no protection during the current season.ConclusionsPersons above 65 years are the largest group at risk for severe or complicated influenza and policy should support their yearly seasonal influenza vaccination, which is to-date the best preventive measure available for all risk groups. No negative effects of repeated seasonal vaccination were seen in this large population-based cohort of older persons with severe influenza, which strengthens the recommendation that persons belonging to this age group should be vaccinated yearly.     

Evidence of bias in estimates of influenza vaccine effectiveness in seniors

BACKGROUND: Numerous observational studies have reported that seniors who receive influenza vaccine are at substantially lower risk of death and hospitalization during the influenza season than unvaccinated seniors. These estimates could be influenced by differences in underlying health status between the vaccinated and unvaccinated groups. Since a protective effect of vaccination should be specific to influenza season, evaluation of non-influenza periods could indicate the possible contribution of bias to the estimates observed during influenza season. METHODS: We evaluated a cohort of 72,527 persons 65 years of age and older followed during an 8 year period and assessed the risk of death from any cause, or hospitalization for pneumonia or influenza, in relation to influenza vaccination, in periods before, during, and after influenza seasons. Secondary models adjusted for covariates defined primarily by diagnosis codes assigned to medical encounters. RESULTS: The relative risk of death for vaccinated persons compared with unvaccinated persons was 0.39 [95% confidence interval (95% CI), 0.33-0.47] before influenza season, 0.56 (0.52-0.61) during influenza season, and 0.74 (0.67-0.80) after influenza season. The relative risk of pneumonia hospitalization was 0.72 (0.59-0.89) before, 0.82 (0.75-0.89) during, and 0.95 (0.85-1.07) after influenza season. Adjustment for diagnosis code variables resulted in estimates that were further from the null, in all time periods. CONCLUSIONS: The reductions in risk before influenza season indicate preferential receipt of vaccine by relatively healthy seniors. Adjustment for diagnosis code variables did not control for this bias. In this study, the magnitude of the bias demonstrated by the associations before the influenza season was sufficient to account entirely for the associations observed during influenza season.     

Racial/ethnic differences in influenza vaccination in the Veterans Affairs Healthcare System

BACKGROUND: Racial/ethnic differences in influenza vaccination exist among elderly adults despite nearly universal Medicare health insurance coverage. Overall influenza vaccination prevalence in the Veterans Affairs (VA) Healthcare System is higher than in the general population; however, it is not known whether racial/ethnic differences exist among older adults receiving VA healthcare. Racial/ethnic differences in influenza vaccination in VA were assessed, and barriers to and facilitators of influenza vaccination were examined among veteran outpatients aged 50 years and older. METHODS: A random sample of 121,738 veterans receiving care at VA outpatient clinics during the 2003-2004 influenza season completed the mailed Survey of Health Experiences of Patients (77% response rate). Multivariate logistic regression was used to examine associations among race/ethnicity and influenza vaccination prevalence, barriers, and facilitators. Analyses were conducted during 2005 and 2006. RESULTS: Based on unadjusted prevalences, non-Hispanic blacks, Hispanics, and American Indian/Alaskan Natives were significantly less likely to be vaccinated for influenza compared to non-Hispanic whites (71%, 79%, and 74%, respectively, vs 82%). After adjustment for age, gender, marital status, education level, employment, having a primary care provider, confidence and/trust in provider, and health status, only non-Hispanic blacks remained significantly less likely to be vaccinated compared to non-Hispanic whites (75% vs 81%). Influenza vaccination barriers and facilitators varied by race/ethnic group. CONCLUSIONS: Compared to non-Hispanic whites, non-Hispanic blacks were less likely to receive influenza vaccination in the VA healthcare system during the 2003-2004 influenza season. Although these differences were small, results suggest the need for further study and culturally informed interventions.     

Missed opportunities to vaccinate older adults in primary care

OBJECTIVE: During the 2000 to 2001 influenza season, distribution of influenza vaccine was delayed, and national self-reported vaccination rates declined. The purposes of this study were to characterize missed opportunities for adult vaccinations and assess the impact of the vaccine delay on missed opportunities for influenza vaccination as recorded in medical records. METHODS: In a cross-sectional analysis, medical record data from 217 adult patients aged > or =65 years in primary care practices that received influenza vaccine supplies late in 2000 were used to assess rates and missed opportunities to vaccinate. Missed opportunities were defined as visits in which there was no record that vaccine had been given, discussed, or refused by the patient. RESULTS: During the mean study period of 37.1 +/- 5.7 months, patients averaged 12.1 +/- 5.9 visits to their primary care physician's office. Medical records indicated that 75% of patients had received pneumococcal polysaccharide vaccine (PPV) and 30% had received tetanus toxoid from 1991 to 2001; 81% had received at least one influenza vaccine in the previous 4 seasons. During the 2000 to 2001 influenza season, influenza vaccination rates declined significantly to 41% from 57% in 1999 to 2000. Overall missed opportunities to vaccinate during the study period averaged 3.4 +/- 3.0 for influenza vaccine, 10.7 +/- 7.3 for pneumococcal vaccine, and 10.8 +/- 5.9 for tetanus toxoid. During the delay season, the number of visits increased, but missed opportunities to vaccinate also increased significantly, even after vaccine supplies had been received. CONCLUSIONS: Missed opportunities to vaccinate occur frequently and vaccine shortages create additional challenges to adult vaccination. Missed opportunities may be minimized and maintenance of accurate adult immunization records may be achieved by assessing and recording vaccination status at each visit, regardless of vaccine availability. By so doing, providers can easily convey the message to their patients that immunizations are an important part of their care.     

Influenza vaccine acceptance and hesitancy among adults hospitalized with severe acute respiratory illnesses,United States 2019–2020

IntroductionUnderstanding patient factors associated with not being vaccinated is essential for successful implementation of influenza vaccination programs.MethodsWe enrolled adults hospitalized with severe acute respiratory illness at 10 United States (US) hospitals during the 2019–2020 influenza season. We interviewed patients to collect data about influenza vaccination, sociodemographic characteristics, and vaccine perceptions.ResultsAmong 679 participants, 264 (38.9%) reported not receiving influenza vaccination. Among those not vaccinated, 135 (51.1%) reported choosing not to receive a vaccine because of perceived ineffectiveness (36.7%) or risk (14.4%) of influenza vaccination. Sociodemographic factors associated with not being vaccinated included no medical insurance (aOR = 6.42; 95% CI: 2.52–16.38) and being non-White or Hispanic (aOR = 1.54, 95% CI: 1.02–2.32).ConclusionsOptimizing uptake of influenza vaccination in the US may be improved by educational programs regarding vaccine safety and effectiveness and enhancing vaccine access, particularly among non-White and Hispanic Americans and those without medical insurance.     

Adherence of mass vaccinators to timing guidelines for influenza vaccination

BACKGROUND: With recent delays in influenza vaccine availability, practitioners have been encouraged to time vaccination activities to promote vaccination of high-priority groups first. This cross-sectional survey of persons vaccinated in nontraditional settings (NTS) by mass vaccinators was conducted to assess how effectively the mass vaccinators were able to implement these vaccination-timing guidelines. METHODS: In Minnesota, the Minnesota Visiting Nurse Agency (MVNA) is a major mass vaccinator in NTS. For the 2001-2002 vaccination season, MVNA developed several strategies designed to facilitate adherence to vaccination timing guidelines adopted by the Minnesota Department of Health. All persons vaccinated in the MVNA NTS clinics from October 2001 through December 2001 were surveyed in order to evaluate whether they were in a high-priority group and whether the timing of their vaccinations coincided with the timing promoted in the guidelines. RESULTS: A total of 46,174 of the 145,947 people vaccinated by the MVNA were vaccinated between October 14 and October 28, 2001, the time period designated for vaccination of high-priority groups. Of these, 41,143 (89%) responded to the priority group question and 27,211 (66%) indicated that they were in one of the targeted groups, including more than 19,000 Medicare recipients. At sites targeting senior citizens, more than 92% of initial vaccine recipients were in a targeted group. Overall, 48.4% of persons vaccinated at any time during the vaccination season were in a high-priority group. CONCLUSIONS: Mass vaccinators can successfully implement influenza vaccination timing guidelines in NTS.     

Influenza vaccination in paediatric nurses: cross-sectional study of coverage, refusal, and factors in acceptance

BACKGROUND: Influenza vaccination among health-care workers is poor, and the effectiveness of hospital vaccination programs remains unclear. Little is known about the effectiveness of intensive evidence-based vaccination programs in nursing staff. We determined whether the recommended vaccination rate could be achieved among paediatric nurses during an intensive promotional program for influenza vaccination. We also sought to identify the reasons for which nurses refuse the influenza vaccine and predictors of future vaccination intent. METHODS: We offered influenza vaccination to nursing staff during an influenza season through a multi-component program that included intensive promotional activities. We analysed vaccination data to determine uptake rates. In a cross-sectional survey, self-administered questionnaires were distributed to all nurses with patient contact during that season. The questionnaire evaluated their vaccine use, site of work, absenteeism and physician visits due to respiratory illness, vaccination intent for the subsequent influenza season, and other items. We surveyed vaccinated nurses regarding their program experiences and the frequency and severity of adverse reactions. Unvaccinated nurses were asked their reasons for refusing vaccination. Multiple logistic-regression analysis was conducted to identify variables that predicted the likelihood of future vaccine acceptance. RESULTS: More than 75% (895/1,182) of applicable nurses were vaccinated in the program. The questionnaire response rate was nearly 48% (585/1,230). Vaccination in the program during the current season (odds ratio [OR] 101.99, 95% confidence interval [CI] 52.54-197.98), program convenience (OR 199.19, 95% CI 98.01-404.11), and a physician visit for respiratory illness (OR 2.44, 95% CI 1.29-4.61) were found to be independent predictors of intent to receive the vaccine the following season. A lack of perceived personal need was the most common reason for vaccine refusal, given in 30% (77/258) of unvaccinated respondents. CONCLUSIONS: Adequate coverage of nurses is achievable during an intensive voluntary immunisation program against influenza, using best-known practices. Perceived lack of personal benefit is a major deterrent, while program convenience and previous vaccination strongly predict future vaccine acceptance. Our findings support interventions that improve the convenience of hospital immunisation programs for influenza, particularly those that are aimed at nurses and that promote vaccine efficacy and benefits.     

Influenza vaccination among the elderly Spanish population: trend from 1993 to 2003 and vaccination-related factors

BACKGROUND: Influenza is an important public health problem that particularly affects elderly subjects and influenza vaccination is a safe, effective and efficient method for prevention of influenza-related complications in elderly individuals with or without underlying chronic conditions. This study aims to analyze adjusted time trends in the coverage of influenza vaccination among elderly Spanish subjects and to identify which variables were associated with the probability of having been vaccinated in 2003. METHODS: We undertook a cross-sectional study using data of individuals aged >/=65 years drawn from the 1993, 1995, 1997, 2001, and 2003 Spanish National Health Surveys. The answer to the question 'Did you have a 'flu shot in the latest campaign' was used as the dependent variable, and socio-demographic and health-related characteristics were analyzed as independent variables. Coverage of vaccination for each year was adjusted by the direct method for both age and gender. Multivariate logistic regression was used to estimate the independent effect of variables on the receipt of influenza vaccine. RESULTS: 15 989 records were analyzed. Adjusted influenza coverage increased from 50.1% in 1993 to 63.7% in 2003 (P < 0.001). The variables that were significantly associated with a higher likelihood of being vaccinated were older age, suffering a chronic disease, residence in towns with <10 000 inhabitants, 'worse' self-perceived health and non-smokers. CONCLUSIONS: Coverage among the Spanish elderly has increased significantly from 1993 to 2003. Still, there is room for improvement, particularly, among the subjects with 'good' self-perceived health, those with no concomitant medical conditions, and smokers.     

Factors associated with continued adherence to influenza vaccination in the elderly

Objective

We aimed to analyze the factors influencing continued adherence to influenza vaccination in elderly persons vaccinated in the preceding season.

Methods

Using a population-based vaccination registry, we evaluated the proportion of persons vaccinated against influenza in Navarre, Spain, in the 2010-11 season among non-institutionalized persons aged 65 years or over who had been vaccinated in the 2009-10 season. Logistic regression was used to analyze the influence of sociodemographic, clinical and health care factors.

Results

Of the 64,245 persons vaccinated against influenza in the 2009-10 season, 87% were vaccinated in the 2010-11 season. Continued adherence to vaccination increased with the number of physician visits per year. It was lower in women, in the 65-69 and ≥ 95 year age-groups, in those hospitalized or diagnosed with any major chronic condition in the previous year, and in persons with hematological cancer or dementia. Health districts and physicians with higher coverage in the previous season continued to have higher adherence in the following season.

Conclusions

People vaccinated against influenza in one season tend to be vaccinated in the following one. Sociodemographic, clinical and health care factors have a moderate effect on the continuity of vaccination, with the most important factor being the treating physician.     

Seasonal influenza vaccination knowledge, risk perception, health beliefs and vaccination behaviours of nurses

The relationship between knowledge, risk perceptions, health belief towards seasonal influenza and vaccination and the vaccination behaviours of nurses was explored. Qualified nurses attending continuing professional education courses at a large London university between 18 April and 18 October 2010 were surveyed (522/672; response rate 77·7%). Of these, 82·6% worked in hospitals; 37·0% reported receiving seasonal influenza vaccination in the previous season and 44·9% reported never being vaccinated during the last 5 years. All respondents were categorized using two-step cluster analyses into never, occasionally, and continuously vaccinated groups. Nurses vaccinated the season before had higher scores of knowledge and risk perception compared to the unvaccinated (P<0·001). Nurses never vaccinated had the lowest scores of knowledge and risk perception compared to other groups (P<0·001). Nurses' seasonal influenza vaccination behaviours are complex. Knowledge and risk perception predict uptake of vaccination in nurses.