Seasonal influenza vaccination coverage in France during two influenza seasons (2007 and 2008) and during a context of pandemic influenza A(H1N1) in 2009

Objectives

To measure the seasonal influenza vaccination coverage rate (VCR) in France in 2009, year of the A(H1N1) influenza pandemic, by age and target disease and compare it with the VCR for the 2007 and 2008 influenza seasons.

Method

At the beginning of each annual seasonal vaccination campaign, the National Health Insurance, covering 86% of the French population, sends free influenza vaccination vouchers to at-risk beneficiaries aged under 65 suffering from diverse chronic diseases and to all individuals aged 65 and over (around 11 million). Vaccination is estimated from refund claims registered in the National Health Insurance Information System.

Results

The global VCR for the target population was 51% in 2007, 55.8% in 2008 and 56.9% in 2009. In 2009, the VCR for children under 10 years old was 24.3%, 28.1% in the 10-19 age range, 39.2% in the 20-64 age range and 63.3% for individuals aged 65 and over, of which 72.3% with a targeted chronic disease and 56.9% without. The inclusion of asthma as a target disease, lowered the global VCR for children under 10 years old (30.6% without asthma) but VCR increased proportionally with the number of annual refunds for drugs against asthma and chronic obstructive pulmonary disease. The 2009 vaccine uptake rates in target group children, adolescents, young adults and to a lesser extent the population aged 65 and over suffering from a chronic disease (particularly chronic respiratory disease), could have been positively impacted by the A(H1N1) influenza context.

Conclusion

The influenza VCR varies considerably according to age and target disease but globally remains inferior to the recommended 75% coverage rate. These results permit the detailed analysis of VCR distribution by disease and target group and highlights areas for reflection and action. Specific studies should be conducted in order to understand why the VCR is lower in certain target groups.     

Longitudinal,population-based cohort study of prenatal influenza vaccination and influenza infection in childhood

BackgroundInfluenza vaccination is recommended to protect mothers and their infants from influenza infection. Few studies have evaluated the health impacts of in utero exposure to influenza vaccine among children more than six months of age.MethodsWe used probabilistically linked administrative health records to establish a mother–child cohort to evaluate the risk of influenza and acute respiratory infections associated with maternal influenza vaccination. Outcomes were laboratory-confirmed influenza (LCI) and hospitalization for influenza or acute respiratory infection (ARI). Adjusted hazard ratios (aHRs) accounted for child’s Aboriginal status and were weighted by the inverse-probability of treatment.Results14,396 (11.5%) children were born to vaccinated mothers. Maternally vaccinated infants aged < 6 months had lower risk of LCI (aHR: 0.33; 95% CI: 0.13, 0.85), influenza-associated hospitalization (aHR: 0.39; 95% CI: 0.16, 0.94) and ARI-associated hospitalization (aHR: 0.85; 95% CI: 0.77, 0.94) compared to maternally unvaccinated infants. With the exception of an increased risk of LCI among children aged 6 months to < 2 years old following first trimester vaccination (aHR: 2.28; 95% CI: 1.41, 3.69), there were no other differences in the risk of LCI, influenza-associated hospitalization or ARI-associated hospitalization among children aged > 6 months.ConclusionStudy results show that maternal influenza vaccination is effective in preventing influenza in the first six months and had no impact on respiratory infections after two years of age.     

Reduced risk of hospitalization associated with influenza vaccination in Canada

To evaluate the effectiveness of influenza vacation, we conducted analyses at both individual level and health region level. The association between influenza vaccination and hospital admission was examined among 128,677 subjects 12+ years of age who participated in a national survey in 2005. Both influenza and hospital admission proportions varied across health regions. Health regions with higher proportions of influenza vaccination had significantly lower proportions of hospitalization. A 10% increase in influenza vaccination less than 1 year ago was associated with a reduction of 11% in the risk of hospitalization over a 12-month time period at the health region level.     

Analysis of public concerns about influenza vaccinations by mining a massive online question dataset in Japan

BackgroundElucidating public concerns regarding vaccinations is important for successful immunization programs. The objective of the present study was to categorize public concerns regarding influenza vaccinations in Japan by analyzing a massive web-based question dataset.MethodsThe Yahoo! Chiebukuro (Japanese Yahoo! Answers) Dataset, which includes more than 16 million questions collected between April 2004 and April 2009, was used in this study. We sequentially filtered data to obtain questions on influenza vaccinations. Any questions that met our exclusion criteria concerning veterinary vaccines or computer virus vaccines were removed from the analysis. Filtered questions and their answers were manually analyzed for their content by a team of board-certified pediatricians.ResultsAfter filtering data, we obtained 1950 questions regarding influenza vaccinations. The three most frequently asked questions were regarding the vaccination schedule, safety, and effectiveness. When we analyzed monthly trends in question contents, we noted the emergence of similar questions in the same period every year. Therefore, we classified the time periods of each year into three parts: (1) from April to the commencement of seasonal influenza vaccinations (September), (2) from October until the epidemic period, and (3) the epidemic period. Two interesting results were obtained: concerns regarding effectiveness abruptly increased during the epidemic period, and pregnant or breastfeeding women increasingly asked questions regarding feasibility between October and the epidemic period.ConclusionsThe questions and concerns collected and analyzed in this study illustrate that the public have questions about the influenza vaccine and also that questions changed with periodical consistency. These results highlight the possible usefulness of providing the public with the latest and correct information to their questions in a timely manner, for example via an official health website.     

Pandemic influenza A(H1N1)pdm09 improves vaccination routine in subsequent years: A cohort study from 2009 to 2011

Background

In 2009 the pandemic influenza virus A(H1N1)pdm09 emerged with guidance that people at risk should be vaccinated. It is unclear how this event affected the underlying seasonal vaccination rate in subsequent years.

Purpose

To investigate the association of pandemic influenza A(H1N1)pdm09 and seasonal flu vaccination status in 2009 with vaccination rates in 2010 and 2011.

Methods

Data were collected in 40 Dutch family practices on patients at risk for influenza during 2009–2011; data analysis was conducted in 2012.

Results

A multilevel logistic regression model (n = 41,843 patients) adjusted for practice and patient characteristics (age and gender, as well as those patient groups at risk), showed that people who were vaccinated against A(H1N1)pdm09 in 2009 were more likely to have been vaccinated in 2010 (OR 6.02; 95%CI 5.62–6.45, p < .0001). This likelihood was even more for people who were vaccinated against seasonal flu in 2009 (OR 13.83; 95%CI 12.93–14.78, p < .0001). A second analysis on the uptake rate in 2011 (n = 39,468 patients) showed that the influence of the vaccination state in 2009 declined after two years, but the diminishing effect was smaller for people vaccinated against A(H1N1)pdm09 than for seasonal flu (OR 5.50; 95%CI 5.13–5.90, p < .0001; OR 10.98; 95%CI 10.26–11.75, p < .0001, respectively).

Conclusion

Being vaccinated against A(H1N1)pdm09 and seasonal influenza in the pandemic year 2009 enhanced the probability of vaccination in the next year and this was still effective in 2011. This suggests that peoples’ vaccination routines were not changed by the rumor around the outbreak of A(H1N1)pdm09, but rather confirmed underlying behavior.     

A comparison of parent and provider reported influenza vaccination status of adolescents

Objective

To compare parent and provider reported influenza vaccination status among adolescents.

Methods

Data from the 2009 National Immunization Survey-Teen (NIS-Teen) were analyzed. The NIS-Teen is a nationally representative random-digit-dialed telephone survey of households with adolescents 13–17 years at the time of interview, followed by a mail survey to the adolescent's vaccination providers to obtain provider-reported vaccination histories. During the interview a parent or guardian was asked if the adolescent had received an influenza vaccination and whether their response was based upon recall only or from consulting a parent-held vaccination record (i.e., shot card) with recall of additional vaccinations not recorded on the shot card. Parent-reported influenza vaccination status was compared with provider-reported vaccination status by calculating various validity measures (sensitivity, specificity, positive predictive value [PPV], negative predictive value [NPV], and kappa), overall and stratified by several demographic characteristics. In the main analysis, provider-reported vaccinations were considered the gold standard. To evaluate the completeness of provider-reporting, we conducted additional analysis that also considered vaccinations reported by parents from the shot card or reported received in a non-medical setting as “true” vaccinations.

Results

During the 2008–2009 season, influenza vaccination coverage among adolescents based on provider report was 11.3%. Based on parent report, influenza vaccination coverage was 21.7%. Twenty-two percent of parents retrieved and referred to a shot card during the interview. In the shot card group, provider versus parent reported coverage was 12.5% versus 18.2% while among the recall only group coverage was 10.9% versus 22.7%, respectively. Overall, compared to provider report as the gold standard, parental report of influenza vaccination had a sensitivity of 86.7%, a specificity of 86.2%, a positive predictive value (PPV) of 43.1%, and a negative predictive value (NPV) of 98.0%. Among the shot card group, of vaccinations reported either by provider or by parent reading vaccination off shot card, only 66% were reported by providers. In the shot card group, the “true” vaccination level (16–17%) was closer to the parent reported coverage when it was assumed that vaccinations read by the parent from a shot card but not reported by a provider were considered true vaccinations. Overall, assuming that providers reported 64% of “true” vaccinations, sensitivity increased to 91%, specificity to 93%, and PPV to 71%.

Conclusions

Overall estimated influenza vaccination coverage was more than ten percentage points higher based on parental report than on provider report, with the difference between provider and parent report greater among the recall only group. The two estimates are closer for those with shot cards, but few parents utilized shot cards in our study and most national surveys do not ask parents to consult shot cards when responding about their adolescent's vaccination. The actual vaccination coverage of adolescents studied is likely between coverage estimates obtained from parent report and provider report.     

Increases in vaccination coverage of healthcare personnel following institutional requirements for influenza vaccination: a national survey of U.S. hospitals

Background

Institutional requirements for influenza vaccination, ranging from policies that mandate declinations to those terminating unvaccinated healthcare personnel (HCP), are increasingly common in the US. Our objective was to determine HCP vaccine uptake following requirements for influenza vaccination at US hospitals.

Methods

Survey mailed in 2011 to a nationally representative sample of 998 acute care hospitals. An institutional requirement was defined as an institutional policy that requires receipt or declination of influenza vaccination, with or without consequences for vaccine refusal. Respondents reported institutional-level, seasonal influenza vaccination coverage, if known, during two consecutive influenza seasons: the season prior to (i.e., pre-requirement), and the first season of requirement (i.e., post-requirement). Weighted univariate and multivariate analyses accounted for sampling design and non-response.

Results

808 (81.0%) hospitals responded. Of hospitals with institutional requirements for influenza vaccination (n = 440), 228 hospitals met analytic inclusion criteria. Overall, mean reported institutional-level influenza vaccination coverage among HCP rose from 62.0% in the pre-requirement season to 76.6% in the post-requirement season, representing a single-season increase of 14.7 (95% CI: 12.6-16.7) percentage points. After adjusting for potential confounders, single-season increases in influenza vaccination uptake remained greater among hospitals that imposed consequences for vaccine refusal, and among hospitals with lower pre-requirement vaccination coverage. Institutional characteristics were not associated with vaccination increases of differential magnitude.

Conclusion

Hospitals that are unable to improve suboptimal influenza vaccination coverage through multi-faceted, voluntary vaccination campaigns may consider institutional requirements for influenza vaccination. Rapid and measurable increases in vaccination coverage followed institutional requirements at hospitals of varying demographic characteristics.     

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.     

Estimating the cost-effectiveness of a national program to eliminate disparities in influenza vaccination rates among elderly minority groups

Influenza is a major cause of preventable morbidity and mortality in the United States, particularly among the elderly. Yet, there remain large disparities in influenza vaccination rates across elderly Caucasian (70%), African-American (50%) and Hispanic (55%) populations, with substantial mortality consequences. In this study, we built a decision-analysis model to estimate the cost-effectiveness of a hypothetical national vaccination program designed to eliminate these disparities in influenza vaccination rates. Taking a societal perspective, we developed a Markov model with a one-year cycle length and lifetime time horizon. In the base case, we conservatively assumed that the cost of promoting the vaccination program was $10 per targeted elder per year and that by year 10, the vaccination rate of the elderly African-American and Hispanic populations would equal the vaccination rate of the elderly Caucasian population (70%). The cost-effectiveness of the vaccination program compared to no vaccination program was $48,617 per QALY saved. Probabilistic sensitivity analyses suggested that at willingness-to-pay thresholds of $50,000 and $100,000 per QALY saved, the likelihood of the vaccination program being cost-effective was 38% and 92%, respectively. In an analysis using conservative assumptions, we found that a hypothetical program to ameliorate disparities in influenza vaccination rates has a moderate to high likelihood of being cost-effective.     

Acceptance of vaccination during pregnancy: experience with 2009 influenza A (H1N1) in the Netherlands

Objectives

In 2009, the Dutch government advised pregnant women to get vaccinated against influenza A (H1N1). A study was set up to gain insight into vaccination coverage and reasons why pregnant women seek vaccination or not.

Methods

We invited 14,529 pregnant women to complete an internet survey on vaccination during pregnancy in general and against 2009 influenza A (H1N1). Differences in background characteristics between unvaccinated and vaccinated women were investigated. Prediction analyses were carried out to determine which survey statement had the greatest impact on vaccination status or intention to get vaccinated during pregnancy.

Results

Of the 2993 included respondents, 63% reported to be vaccinated against 2009 influenza A (H1N1). Vaccination coverage was higher among older birth cohorts, women who had been pregnant before, women with underlying medical conditions, and women who reported no defined ‘life philosophy’. Protection of the child (after birth), the government's advice and possible harmful effects of the vaccine for the unborn child had the greatest predictive value for vaccination status. With regards vaccination during future pregnancies, 39% had a positive intention to obtain vaccination and 45% were neutral. The government's advice was the strongest predictor for intention. Furthermore, women expressed concern over lack of sufficient knowledge about vaccine safety.

Conclusions

A considerable number of pregnant women in the Netherlands reported to be vaccinated against 2009 influenza A (H1N1). The challenge for the government in the future will be to provide pregnant women and health care professionals with sufficient and clear information about disease severity and the benefits and safety of vaccination.     

Barriers and facilitators to uptake and promotion of influenza vaccination among health care workers in the community in Beijing,China: A qualitative study

BackgroundIn the prevention and control of influenza, it is important for healthcare workers (HCWs) to be vaccinated and recommend influenza vaccines to their patients. However, there is limited evidence on the factors influencing uptake and promotion of influenza vaccination to patients among HCWs in China.MethodsWe conducted in-depth interviews among HCWs in community health centers, including general practitioners (GPs) and preventive health workers (PHWs), during January to February 2017. A total of 21 individuals, purposively selected from six community health centers covering central districts and remote suburbs in Beijing, were interviewed using semi-structured topic guides. Thematic analysis was used to analyze the interviews and coding framework was developed both inductively and deductively.ResultsIdentified factors influencing influenza vaccine uptake included knowledge, perception and recognition, and prior experience of vaccine uptake. All PHWs conservatively recommended influenza vaccine because of concerns about potential patient–doctor disputes. GPs rarely recommended vaccination under their own initiative because vaccine promotion was not their duties. Notably, we found that the division of work was an underlying reason for the different behaviors regarding vaccine uptake and promotion between GPs and PHWs.ConclusionsOur findings highlighted a combination of misconceptions and cognitive biases limiting influenza vaccine uptake among HCWs in China. Our findings indicate that promotion of health education regarding influenza vaccination should be implemented among HCWs. Importantly, the division of work greatly affects the behaviors of HCWs. GPs, who are at the front line in the doctor–patient relationship, have a critical role in influenza vaccination programs.     

Social and demographic patterns of influenza vaccination coverage in Norway,influenza seasons 2014/15 to 2020/21

AimsTo examine influenza vaccination coverage among risk groups (RG) and health care workers (HCW), and study social and demographic patterns of vaccination coverage over time.MethodsVaccination coverage was estimated by self-report in a nationally representative telephone survey among 14 919 individuals aged 18–79 years over seven influenza seasons from 2014/15 to 2020/21. We explored whether belonging to an influenza RG (being >=65 years of age and/or having >=1 medical risk factor), being a HCW or educational attainment was associated with vaccination status using logistic regression.ResultsVaccination coverage increased from 27 % to 66 % among individuals 65–79 years, from 13 % to 33 % among individuals 18–64 years with >=1 risk factor, and from 9 % to 51 % among HCWs during the study period. Being older, having a risk factor or being a HCW were significantly associated with higher coverage in all multivariable logistic regression analyses. Higher education was also consistently associated with higher coverage, but the difference did not reach significance in all influenza seasons. Educational attainment was not significantly associated with coverage while coverage was at its lowest (2014/15–2017/18), but as coverage increased, so did the differences. Individuals with intermediate or lower education were less likely to report vaccination than those with higher education in season 2018/19, OR = 0.61 (95 % CI 0.46–0.80) and OR = 0.58 (95 % CI 0.41–0.83), respectively, and in season 2019/20, OR = 0.69 (95 % CI 0.55–0.88) and OR = 0.71 (95 % CI 0.53–0.95), respectively. When the vaccine was funded in the COVID-19 pandemic winter of 2020/21, educational differences diminished again and were no longer significant.ConclusionsWe observed widening educational differences in influenza vaccination coverage as coverage increased from 2014/15 to 2019/20. When influenza vaccination was funded in 2020/21, differences in coverage by educational attainment diminished. These findings indicate that economic barriers influence influenza vaccination decisions among risk groups in Norway.     

Influenza vaccination in Austria from 1982 to 2011: A country resistant to influenza prevention and control

Background

Austria's position on influenza vaccination is unique. Generally it is recommended for everyone, and specifically for those over the age of 50 years and all children between 6 months and 5 years. However, the vaccination rate among the general public is one of the lowest in the world (<10%). Our objective was to provide baseline information to allow a better understanding of the low vaccination rate.

Methods

This paper presents data on influenza vaccine use in Austria during a period of almost 30 years, from 1982 to 2011. Data presented in this study were obtained from three sources.

Results

Between 1982 and 1992, Austria showed little change in its low proportion of vaccinations (from 20 to 23 doses/1000); from 1992 to 1995, the proportion increased to 52 doses/1000, retaining its status as one of the low-use countries. By 2003, the proportion had increased to 127 doses/1000, but Austria remained one of the three lowest-use Western European countries. Between 2007 and 2011/2012, a steady decrease to 81 doses/1000 was observed.

Conclusion

The Austrian population, and parts of the medical system, have shown distinct ignorance regarding the prevention and control of influenza over past decades. Possible reasons for this development are discussed.     

Evaluation of self-reported and registry-based influenza vaccination status in a Wisconsin cohort

We evaluated influenza vaccination status as determined by self-report and a regional, real-time immunization registry during two influenza seasons when subjects were enrolled in a study to estimate vaccine effectiveness. We enrolled 2907 patients during the two consecutive seasons. The sensitivity and specificity of self-reported influenza vaccination when compared to immunization registry records were 95% and 90%, respectively. The positive predictive value of self-reported vaccination was 89% and negative predictive value was 96%. In our study population, self-reported influenza vaccine status was a sensitive and fairly specific indicator of actual vaccine status. Misclassification was more common among young children.     

Vaccine complacency and dose distribution inequities limit the benefits of seasonal influenza vaccination,despite a positive trend in use

Sustainable demand for seasonal influenza vaccines is a component of national security strategies for pandemic preparedness. However, the ongoing COVID-19 pandemic has revealed many weaknesses in the capacity of countries to design and execute sustainable vaccination programs. An influenza pandemic remains a global threat and yet there is no global monitoring system for assessing progress towards influenza vaccination coverage targets. The International Federation of Pharmaceutical Manufacturers and Associations’ (IFPMA) Influenza Vaccine Supply International Task Force (IVS) developed a survey method in 2008 to estimate seasonal influenza vaccination coverage rates, which in turn serves as a crude estimate of pandemic preparedness. It provides evidence to guide expanded efforts for pandemic preparedness, specifically for increasing COVID-19 vaccine immunization levels. Furthermore, the results presented herein serve as a proxy for assessing the state of pandemic preparedness at a global and regional level. This paper adds data from 2018 and 2019 to the previous analyses. The current data show an upward or stable global trend in seasonal influenza vaccine dose distributed per 1,000 population with a 7% increase between 2017 and 2018 and 6% increase between 2018 and 2019. However, considerable regional inequities in access to vaccine persist. Three regions, Africa, the Middle-east, and Southeast Asia together account for 50% of the global population but only 6% of distributed seasonal influenza vaccine doses. This is an important finding in the context of the ongoing COVID-19 pandemic, as distribution of influenza vaccine doses in many ways reflects access to COVID-19 vaccines. Moreover, improving seasonal vaccine uptake rates is critical for optimizing the annual benefits by reducing the huge annual influenza-associated societal burdens and by providing protection to vulnerable individuals against serious complications from seasonal influenza infections.     

Achieving optimal influenza vaccination rates: a survey-based study of healthcare workers in an urban hospital

In the USA, more than 36 000 deaths and 114 000 hospitalisations result from the influenza virus annually. Healthcare workers have been identified as a key source of influenza outbreaks. Despite Centers for Disease Control and Prevention recommendations to vaccinate all healthcare workers, the rate remains low. A survey-based investigation of influenza vaccination rates and related factors was carried out in an urban community teaching medical centre. A total of 570 surveys revealed a 56.5% influenza vaccination rate among participants. Participants who received the vaccine had a significantly higher mean influenza knowledge score compared to those who did not receive the vaccine (P=0.003). Also, a relationship was identified between those who received the vaccine and the perception that the purpose of the vaccine is to prevent patients from being exposed to influenza (P=0.001). Lastly, hospital departments in which managers actively encouraged and facilitated vaccination had higher rates in general.