Influenza vaccine effectiveness in preventing hospitalization among the elderly during influenza type A and type B seasons

Effects of Vaccine Literacy, Health Beliefs, and Flu Vaccination on Perceived Physical Health Status among Under/Graduate Students

Physicians highlight that receiving the flu vaccine is critical, especially during the COVID-19 pandemic period. Younger groups' flu vaccination coverage is very low, and this tendency is potentially related to a lower level of vaccine literacy and perceptions toward vaccination. This study investigated the relationship between flu vaccine literacy, health beliefs, and flu vaccinations (benefit, barrier, severity, and susceptibility) and their impact on perceived health status controlling for socioeconomic factors. It used the Health Belief Model andHealth Literacy Skills Framework with under/graduate students (N = 382) in Ohio, U.S. Path analyses were performed to examine the causal process using SPSS and Amos 23.0. Indicators of CFI, RMSEA, SRMR, and the chi-square/df of the path models were good-acceptable. Vaccine literacy directly impacted on health beliefs and vaccination. Susceptibility belief directly influenced perceived health status. The mediation effects of health beliefs (benefit, barrier) between vaccine literacy and vaccination were confirmed. The study highlights the need for healthcare providers and governments to work together to improve flu vaccine literacy and reduce negative perceptions toward vaccination among younger populations. Educational programs and official communication channels can be used to address concerns and provide accurate information about vaccines to increase flu vaccination rates and protect public health.

A Systematic Review and Meta-Analysis of the Relationship between Receiving the Flu Vaccine with Acute Cerebrovascular Accident and Its Hospitalization in the Elderly

Background and Aims

In recent years, various studies have been conducted worldwide to investigate the relationship between receiving the flu vaccine with acute cerebrovascular accident or stroke and its hospitalization in the elderly; however, the results of these studies are contradictory. Therefore, this study was aimed at investigating the relationship between receiving the flu vaccine with stroke and its hospitalization in the elderly.

Methods

This study is a systematic review and meta-analysis of studies examining the relationship between receiving the flu vaccine with stroke and its hospitalization in the elderly during the years 1980 to 2021 which have been published in ISI Web of Science, Scopus PubMed, Cochrane, Science Direct, Google Scholar, and Embase. All analyses were performed by Stata 15, and the significance level in this study was considered <0.05.

Results

In the systematic search, 3088 articles were retrieved, considering the study criteria; finally, 14 studies were included in the meta-analysis. Based on the results of the meta-analysis, the odds ratio (OR) of occurrence and hospitalization of stroke compared to the nonvaccinated group in vaccine recipients is equal to 0.84 (95% confidence interval (CI): 0.78-0.90, P value ≤ 0.001). Publication bias was not observed in this study (P value = 0.101).

Conclusion

Getting the flu vaccine can reduce the risk of occurrence and hospitalization of stroke in the elderly by 16% (10%-22%). Therefore, receiving this vaccine as a preventive intervention for stroke in the elderly may be promising.

A New Master Donor Virus for the Development of Live-Attenuated Influenza B Virus Vaccines

Influenza B viruses (IBV) circulate annually, with young children, the elderly and immunocompromised individuals being at high risk. Yearly vaccinations are recommended to protect against seasonally influenza viruses, including IBV. Live attenuated influenza vaccines (LAIV) provide the unique opportunity for direct exposure to the antigenically variable surface glycoproteins as well as the more conserved internal components. Ideally, LAIV Master Donor Viruses (MDV) should accurately reflect seasonal influenza strains. Unfortunately, the continuous evolution of IBV have led to significant changes in conserved epitopes compared to the IBV MDV based on B/Ann Arbor/1/1966 strain. Here, we propose a recent influenza B/Brisbane/60/2008 as an efficacious MDV alternative, as its internal viral proteins more accurately reflect those of circulating IBV strains. We introduced the mutations responsible for the temperature sensitive (ts), cold adapted (ca) and attenuated (att) phenotype of B/Ann Arbor/1/1966 MDV LAIV into B/Brisbane/60/2008 to generate a new MDV LAIV. In vitro and in vivo analysis demonstrated that the mutations responsible of the ts, ca, and att phenotype of B/Ann Arbor/1/1966 MDV LAIV were able to infer the same phenotype to B/Brisbane/60/2008, demonstrating its potential as a new MDV for the development of LAIV to protect against contemporary IBV strains.

Effects of Health Beliefs on Flu Vaccination and Physical Health among Under/Graduate Students in the U.S.: Racial Differences (Whites, African Americans, Hispanics, and Asians)

Physicians highlight that annual flu vaccination is the best strategy for preventing seasonal flu and flu-associated complications and it reduces the burden of infectious diseases. Path analyses were used to understand whether health beliefs (barriers, benefits, susceptibility, severity) influence flu vaccinations, in turn, enhance self-rated health of White, African American, Hispanic, and Asian adults in the U.S. (N = 446). Multiple-group analyses were performed to see whether given paths vary across the four groups. Regardless of race, perceived barriers and benefits significantly influenced flu vaccination. There was a group variance in the path-model of the perceived barriers, flu vaccination, and self-rated health. Although the direct effect of perceived barriers on flu vaccination was shown for all racial groups, the direct effect of perceived barriers on self-rated health was shown only for Asians. Social workers and healthcare providers should be educated to appropriately interpret different meanings of health beliefs of diverse racial groups.

Effects of influenza immunization on pneumonia in the elderly

Influenza virus is a common pathogen implicated in respiratory tract infections, annually affecting up to 20% of the general population, and pneumonia is a leading cause of death after influenza infection. Post-influenza pneumonia is especially common in the elderly and chronically ill patients. The risk of post-influenza pneumonia is significantly increased according to the number of concurrent comorbidities. Vaccination is the primary measure used to abate influenza epidemics and associated complications. In meta-analyses, influenza vaccine significantly reduces pneumonia- and influenza-related hospitalizations, with a vaccine effectiveness of 25-53%. However, considering the poor effectiveness of conventional influenza vaccines in the elderly, several highly immunogenic influenza vaccines have been developed. Further evaluations of the comparative effectiveness of diverse vaccine formulations are warranted to assess their utility for preventing influenza infection, post-influenza pneumonia, and related hospitalization/mortality. Based on cost-effectiveness and budget impact analysis, influenza vaccination strategies should be tailored in the elderly.

Vaccines for preventing influenza in the elderly

BACKGROUND

The consequences of influenza in the elderly (those age 65 years or older) are complications, hospitalisations, and death. The primary goal of influenza vaccination in the elderly is to reduce the risk of death among people who are most vulnerable. This is an update of a review published in 2010. Future updates of this review will be made only when new trials or vaccines become available. Observational data included in previous versions of the review have been retained for historical reasons but have not been updated because of their lack of influence on the review conclusions.

OBJECTIVES

To assess the effects (efficacy, effectiveness, and harm) of vaccines against influenza in the elderly.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library 2016, Issue 11), which includes the Cochrane Acute Respiratory Infections Group's Specialised Register; MEDLINE (1966 to 31 December 2016); Embase (1974 to 31 December 2016); Web of Science (1974 to 31 December 2016); CINAHL (1981 to 31 December 2016); LILACS (1982 to 31 December 2016); WHO International Clinical Trials Registry Platform (ICTRP; 1 July 2017); and ClinicalTrials.gov (1 July 2017).

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs assessing efficacy against influenza (laboratory-confirmed cases) or effectiveness against influenza-like illness (ILI) or safety. We considered any influenza vaccine given independently, in any dose, preparation, or time schedule, compared with placebo or with no intervention. Previous versions of this review included 67 cohort and case-control studies. The searches for these trial designs are no longer updated.

DATA COLLECTION AND ANALYSIS

Review authors independently assessed risk of bias and extracted data. We rated the certainty of evidence with GRADE for the key outcomes of influenza, ILI, complications (hospitalisation, pneumonia), and adverse events. We have presented aggregate control group risks to illustrate the effect in absolute terms. We used them as the basis for calculating the number needed to vaccinate to prevent one case of each event for influenza and ILI outcomes.

MAIN RESULTS

We identified eight RCTs (over 5000 participants), of which four assessed harms. The studies were conducted in community and residential care settings in Europe and the USA between 1965 and 2000. Risk of bias reduced our certainty in the findings for influenza and ILI, but not for other outcomes.Older adults receiving the influenza vaccine may experience less influenza over a single season compared with placebo, from 6% to 2.4% (risk ratio (RR) 0.42, 95% confidence interval (CI) 0.27 to 0.66; low-certainty evidence). We rated the evidence as low certainty due to uncertainty over how influenza was diagnosed. Older adults probably experience less ILI compared with those who do not receive a vaccination over the course of a single influenza season (3.5% versus 6%; RR 0.59, 95% CI 0.47 to 0.73; moderate-certainty evidence). These results indicate that 30 people would need to be vaccinated to prevent one person experiencing influenza, and 42 would need to be vaccinated to prevent one person having an ILI.The study providing data for mortality and pneumonia was underpowered to detect differences in these outcomes. There were 3 deaths from 522 participants in the vaccination arm and 1 death from 177 participants in the placebo arm, providing very low-certainty evidence for the effect on mortality (RR 1.02, 95% CI 0.11 to 9.72). No cases of pneumonia occurred in one study that reported this outcome (very low-certainty evidence). No data on hospitalisations were reported. Confidence intervaIs around the effect of vaccines on fever and nausea were wide, and we do not have enough information about these harms in older people (fever: 1.6% with placebo compared with 2.5% after vaccination (RR 1.57, 0.92 to 2.71; moderate-certainty evidence)); nausea (2.4% with placebo compared with 4.2% after vaccination (RR 1.75, 95% CI 0.74 to 4.12; low-certainty evidence)).

AUTHORS' CONCLUSIONS

Older adults receiving the influenza vaccine may have a lower risk of influenza (from 6% to 2.4%), and probably have a lower risk of ILI compared with those who do not receive a vaccination over the course of a single influenza season (from 6% to 3.5%). We are uncertain how big a difference these vaccines will make across different seasons. Very few deaths occurred, and no data on hospitalisation were reported. No cases of pneumonia occurred in one study that reported this outcome. We do not have enough information to assess harms relating to fever and nausea in this population.The evidence for a lower risk of influenza and ILI with vaccination is limited by biases in the design or conduct of the studies. Lack of detail regarding the methods used to confirm the diagnosis of influenza limits the applicability of this result. The available evidence relating to complications is of poor quality, insufficient, or old and provides no clear guidance for public health regarding the safety, efficacy, or effectiveness of influenza vaccines for people aged 65 years or older. Society should invest in research on a new generation of influenza vaccines for the elderly.

Replication-competent fluorescent-expressing influenza B virus

Influenza B viruses (IBVs) cause annual outbreaks of respiratory illness in humans and are increasingly recognized as a major cause of influenza-associated morbidity and mortality. Studying influenza viruses requires the use of secondary methodologies to identify virus-infected cells. To this end, replication-competent influenza A viruses (IAVs) expressing easily traceable fluorescent proteins have been recently developed. In contrast, similar approaches for IBV are mostly lacking. In this report, we describe the generation and characterization of replication-competent influenza B/Brisbane/60/2008 viruses expressing fluorescent mCherry or GFP fused to the C-terminal of the viral non-structural 1 (NS1) protein. Fluorescent-expressing IBVs display similar growth kinetics and plaque phenotype to wild-type IBV, while fluorescent protein expression allows for the easy identification of virus-infected cells. Without the need of secondary approaches to monitor viral infection, fluorescent-expressing IBVs represent an ideal approach to study the biology of IBV and an excellent platform for the rapid identification and characterization of antiviral therapeutics or neutralizing antibodies using high-throughput screening approaches. Lastly, fluorescent-expressing IBVs can be combined with the recently described reporter-expressing IAVs for the identification of novel therapeutics to combat these two important human respiratory pathogens.

Frequency and impact of confounding by indication and healthy vaccinee bias in observational studies assessing influenza vaccine effectiveness: a systematic review

Background

Evidence on influenza vaccine effectiveness (VE) is commonly derived from observational studies. However, these studies are prone to confounding by indication and healthy vaccinee bias. We aimed to systematically investigate these two forms of confounding/bias.

Methods

Systematic review of observational studies reporting influenza VE and indicators for bias and confounding. We assessed risk of confounding by indication and healthy vaccinee bias for each study and calculated ratios of odds ratios (crude/adjusted) to quantify the effect of confounder adjustment. VE-estimates during and outside influenza seasons were compared to assess residual confounding by healthy vaccinee effects.

Results

We identified 23 studies reporting on 11 outcomes. Of these, 19 (83 %) showed high risk of bias: Fourteen due to confounding by indication, two for healthy vaccinee bias, and three studies showed both forms of confounding/bias. Adjustment for confounders increased VE on average by 12 % (95 % CI: 7–17 %; all-cause mortality), 9 % (95 % CI: 4–14 %; all-cause hospitalization) and 7 % (95 % CI: 4–10 %; influenza-like illness). Despite adjustment, nine studies showed residual confounding as indicated by significant off-season VE-estimates. These were observed for five outcomes, but more frequently for all-cause mortality as compared to other outcomes (p = 0.03) and in studies which indicated healthy vaccinee bias at baseline (p = 0.01).

Conclusions

Both confounding by indication and healthy vaccinee bias are likely to operate simultaneously in observational studies on influenza VE. Although adjustment can correct for confounding by indication to some extent, the resulting estimates are still prone to healthy vaccinee bias, at least as long as unspecific outcomes like all-cause mortality are used. Therefore, cohort studies using administrative data bases with unspecific outcomes should no longer be used to measure the effects of influenza vaccination.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1154-y) contains supplementary material, which is available to authorized users.

Flu Vaccination

The research presented in this article exposes a wide gap between evidence and public policy with regard to influenza vaccination in the context of the 2009 pandemic and with regard to yearly seasonal epidemics. It shows that the World Health Organization and health authorities worldwide failed to protect the interests of the most vulnerable during the 2009 flu pandemic and demonstrates a lack of scientific base for seasonal flu vaccination campaigns. Narrowing the gap between scientific evidence and public health policies with regard to influenza is a serious and urgent matter, one that implies confronting the interests of big pharmaceutical corporations and their allies at academic and government levels. The credibility of science and the well-being of many are at stake.

Influenza vaccination reduces hospitalization for acute coronary syndrome in elderly patients with chronic obstructive pulmonary disease: a population-based cohort study

BACKGROUND

Elderly patients with chronic obstructive pulmonary disease (COPD) are at a higher risk of hospitalization for cardiovascular complications, especially during respiratory infections. Previous studies showed that vaccination for influenza may reduce the risk of recurrent major cardiovascular events in patients with acute coronary syndrome (ACS). The purpose of this study was to evaluate the hypothesis that influenza vaccination could reduce hospitalizations for ACS in elderly patients with COPD.

METHOD

Using the Taiwan Longitudinal Health Insurance Database 1996-2008, this cohort study comprised elderly patients (≥ 55 years old) with a recorded diagnosis of COPD (n=7722) between January 1, 2000 and December 31, 2007. Each patient was followed until the end of 2007. A propensity score was derived by using a logistic regression model to reduce vaccine therapy selection bias. The hazard ratio (HR) and 95% confidence interval (CI) for the association between the influenza vaccination and the occurrence of first hospitalization for ACS in elderly COPD patients was examined by Cox proportional hazards regression analysis. In addition, we categorized the patients into four groups according to vaccination status (unvaccinated, total number of vaccinations: 1, 2-3, and ≥ 4).

RESULTS

We found that elderly patients with COPD receiving influenza vaccination had a lower risk of hospitalization for ACS (adjusted HR=0.46, 95% CI (0.39-0.55), p < 0.001). We observed similar protective effects in both sexes and all age groups (55-64, 65-74, ≥ 75) regardless of influenza seasonality. When the patients were stratified according to the total number of vaccinations, the adjusted HRs for hospitalization because of ACS were 0.48 (0.38-0.62) and 0.20 (0.14-0.28) for patients who received 2-3 and ≥ 4 vaccinations during the follow-up period.

CONCLUSION

Our data showed that there was a lower risk of ACS hospitalization in elderly patients with COPD receiving annual influenza vaccination.

Viral-bacterial interactions-therapeutic implications

Viral and bacterial respiratory tract infections are a leading cause of morbidity and mortality worldwide, despite the development of vaccines and potent antibiotics. Frequently, viruses and bacteria can co‐infect the same host, resulting in heightened pathology and severity of illness compared to single infections. Bacterial superinfections have been a significant cause of death during every influenza pandemic, including the 2009 H1N1 pandemic. This review will analyze the epidemiology and global impact of viral and bacterial co‐infections of the respiratory tract, with an emphasis on bacterial infections following influenza. We will next examine the mechanisms by which viral infections enhance the acquisition and severity of bacterial infections. Finally, we will discuss current management strategies for diagnosing and treating patients with suspected or confirmed viral‐bacterial infections of the respiratory tract. Further investigation into the interactions between viral and bacterial infections is necessary for developing new therapeutic approaches aimed at mitigating the severity of co‐infections.

Double dose vs. standard dose influenza vaccination in patients with heart failure: a pilot study

AIMS

Influenza infection leads to increased morbidity and mortality in those with heart failure, and individuals with heart failure exhibit reduced antibody responses to influenza vaccine. We hypothesized that patients with heart failure randomized to double dose (DD) influenza vaccine will mount more vigorous humoral immune responses compared with those given standard dose (SD) vaccine.

METHODS AND RESULTS

We randomized 28 heart failure patients to DD (30 μg/strain) or SD (15 μg/strain) influenza vaccine. We assessed antibody production by haemagglutination inhibition assay (reported as log haemagglutination units) prior to, at 2-4 weeks and at 4-6 months following vaccination. Baseline antibody titres between DD (n = 12, mean age 64 ± 10 years) and SD (n = 16, mean age 63 ± 9 years) did not differ significantly. At 2-4 weeks, DD haemagglutination unit changes were significantly higher than those of SD (3.3 vs. 1.6 for A/H3N2, P < 0.001; 1.9 and 1.1 for A/H1N1, P = 0.009; and 1.7 and 1 for B-type, P = 0.02). At 4-6 weeks, there were no differences in titres in any of the virus types between treatment groups and, although titres decreased, levels remained above the seroprotective threshold.

CONCLUSIONS

Higher influenza vaccine doses may elicit increased antibody-mediated responses in patients with heart failure; further studies should assess whether clinical outcomes are improved with this strategy.

Effectiveness of adjuvanted seasonal influenza vaccines (Inflexal V ® and Fluad ® ) in preventing hospitalization for influenza and pneumonia in the elderly: a matched case-control study

Annual vaccination is the main mean of preventing influenza in the elderly. In order to evaluate the effectiveness of the adjuvanted seasonal influenza vaccines available in Italy in preventing hospitalization for influenza and pneumonia, a matched case-control study was performed in elderly subjects during the 2010–2011 season in Genoa (Italy). Cases and controls were matched in a 1:1 ratio according to gender, age, socio-economic status and type of influenza vaccine. Vaccine effectiveness was calculated as IVE = [(1-OR)x100] and crude odds ratios were estimated through conditional logistic regression models. Adjusted odds ratios were estimated through multivariable logistic models.

In the study area, influenza activity was moderate in the 2010–2011 season, with optimal matching between circulating viruses and vaccine strains. We recruited 187 case-control pairs; 46.5% of cases and 79.1% of controls had been vaccinated. The adjuvanted influenza vaccines (Fluad^® considered together with Inflexal V^®) were associated with a significant reduction in the risk of hospitalization, their effectiveness being 94.8% (CI 77.1–98.8). Adjusted vaccine effectiveness was 95.2% (CI 62.8–99.4) and 87.8 (CI 0.0–98.9) for Inflexal V^® and Fluad^®, respectively. Both adjuvanted vaccines proved effective, although the results displayed statistical significance only for Inflexal V^® (p = 0.004), while for Fluad^® statistical significance was not reached (p = 0.09). Our study is the first to provide information on the effectiveness of Inflexal V^® in terms of reducing hospitalizations for influenza or pneumonia in the elderly, and demonstrates that this vaccine yields a high degree of protection and that its use would generate considerable saving for the National Health Service.

Efficacy of influenza vaccine among elderly patients by physical activity status

OBJECTIVE

Although many studies have shown the usefulness of influenza vaccine in elderly in-patients, the efficacy of vaccination with regard to the daily physical activities of patients has not been fully evaluated. To address this issue, we correlated the use of medical resources with vaccination status in patients categorized according to their daily activity levels.

METHODS

The subjects comprised 237 in-patients at or above 51 years of age, who were hospitalized in the long-term care unit of a Japanese hospital between January and March, 1999. The vaccination status and medical resources use (i.e., oral antibiotics, injected antibiotics, blood cell count, chest X-ray) of each patient were recorded, and the patients were assigned to three subgroups, based on daily life activity scores.

RESULTS

Vaccinated in-patients in the 'bed-bound' category required fewer medical resources, i.e., oral antibiotics (-2.29 days,P<0.05), injected antibiotics (-5.02 days,P<0.001), blood cell counts (-4.66 times,P<0.001), and chest X-rays (-4.31 times,P<0.001), compared with unvaccinated in-patients. There were no significant differences in treatment parameters between vaccinated and unvaccinated patients in the 'partly limited' or 'no limitation' categories.

CONCLUSIONS

It is suggested that influenza vaccination significantly reduces the need for medical treatment only among those in-patients who are the least physically active. Further studies are required to replicate these findings, and to elucidate the underlying reasons for this reduction.

Unexpected severity of cases of influenza B infection in patients that required hospitalization during the first postpandemic wave

OBJECTIVES

After the last pandemic the knowledge regarding influenza A infection has improved however, the outcomes of influenza B infection remain poorly studied. The aim of this study was to compare the features of influenza B versus influenza A(H1N1)pdm09 infections during the 2010-2011 epidemic-season.

METHODS

A prospective, observational-cohort of adults with laboratory-confirmed influenza infection during the 2010-2011 epidemic-season was studied

RESULTS

Fifty cases of influenza B and 80 of influenza A(H1N1)pdm09 infection were enrolled. Among patients with influenza B, the median age was 34 years-old (23-64), 30% pregnant, 24% obese, 34% transplant recipients and 14% with bacterial co-infection. Twenty-eight percent of patients had pneumonia with alveolar localized pattern and five (10%) died. Pneumonia was associated with delayed antiviral therapy, older age, higher Charlson score, invasive mechanical ventilation and bacterial co-infection. Obesity and pregnancy were not associated with complicated influenza B infection. The proportion of pneumonia, admission to the ICU and mortality did not differ between cases of influenza A(H1N1)pdm09 and influenza B infection.

CONCLUSIONS

Influenza B infection causes severe infection and it is associated with pneumonia or death, similar to influenza A(H1N1)pdm09 infection. Rapid diagnosis and early antiviral therapy are necessary for managing influenza pneumonia during epidemic periods.

Transmission of influenza B viruses in the guinea pig

Epidemic influenza is typically caused by infection with viruses of the A and B types and can result in substantial morbidity and mortality during a given season. Here we demonstrate that influenza B viruses can replicate in the upper respiratory tract of the guinea pig and that viruses of the two main lineages can be transmitted with 100% efficiency between inoculated and naïve animals in both contact and noncontact models. Our results also indicate that, like in the case for influenza A virus, transmission of influenza B viruses is enhanced at colder temperatures, providing an explanation for the seasonality of influenza epidemics in temperate climates. We therefore present, for the first time, a small animal model with which to study the underlying mechanisms of influenza B virus transmission.

Influenza vaccine effectiveness in the elderly based on administrative databases: change in immunization habit as a marker for bias

BACKGROUND

Administrative databases provide efficient methods to estimate influenza vaccine effectiveness (IVE) against severe outcomes in the elderly but are prone to intractable bias. This study returns to one of the linked population databases by which IVE against hospitalization and death in the elderly was first assessed. We explore IVE across six more recent influenza seasons, including periods before, during, and after peak activity to identify potential markers for bias.

METHODS AND FINDINGS

Acute respiratory hospitalization and all-cause mortality were compared between immunized/non-immunized community-dwelling seniors ≥65 years through administrative databases in Manitoba, Canada between 2000-01 and 2005-06. IVE was compared during pre-season/influenza/post-season periods through logistic regression with multivariable adjustment (age/sex/income/residence/prior influenza or pneumococcal immunization/medical visits/comorbidity), stratification based on prior influenza immunization history, and propensity scores. Analysis during pre-season periods assessed baseline differences between immunized and unimmunized groups. The study population included ∼140,000 seniors, of whom 50-60% were immunized annually. Adjustment for key covariates and use of propensity scores consistently increased IVE. Estimates were paradoxically higher pre-season and for all-cause mortality vs. acute respiratory hospitalization. Stratified analysis showed that those twice consecutively and currently immunized were always at significantly lower hospitalization/mortality risk with odds ratios (OR) of 0.60 [95%CI0.48-0.75] and 0.58 [0.53-0.64] pre-season and 0.77 [0.69-0.86] and 0.71 [0.66-0.77] during influenza circulation, relative to the consistently unimmunized. Conversely, those forgoing immunization when twice previously immunized were always at significantly higher hospitalization/mortality risk with OR of 1.41 [1.14-1.73] and 2.45 [2.21-2.72] pre-season and 1.21 [1.03-1.43] and 1.78 [1.61-1.96] during influenza circulation.

CONCLUSIONS

The most pronounced IVE estimates were paradoxically observed pre-season, indicating bias tending to over-estimate vaccine protection. Change in immunization habit from that of the prior two years may be a marker for this bias in administrative data sets; however, no analytic technique explored could adjust for its influence. Improved methods to achieve valid interpretation of protection in the elderly are needed.

[Study on the adverse effects and protective effects of influenza vaccine among elderly individuals vaccinated through the public system in the municipality of Tubarão, State of Santa Catarina]

INTRODUCTION

The aim of this study was to investigate the incidence of adverse effects and protective effects from influenza vaccine among elderly individuals who were vaccinated through the public healthcare system in the municipality of Tubarão, State of Santa Catarina.

METHODS

A prospective cohort study was conducted between May and September 2008. A group of 341 patients was recruited, among whom 289 had been vaccinated through the public system (VSUS) and 52 had not been vaccinated (NV). The incidence of protective effects was observed by comparing the VSUS and NV groups.

RESULTS

It was observed that 22.5% of the vaccinated subjects exhibited at least one adverse effect. Comparing the VSUS and NV groups in relation to the incidence of flu symptoms presented during the winter, at least one symptom was observed in 47% and 28.8% (RR = 1.11; 1.02-1.22; p = 0.0156), respectively.

CONCLUSIONS

These findings demonstrate that the incidence of adverse effects was low. The high incidence of flu symptoms in the VSUS group, in comparison with NV, may be related to the profile of subjects who are in the habit of getting vaccinated against influenza.

Seasonal influenza vaccinations: specialized products for different target groups

Traditionally, inactivated influenza vaccines have all been treated as virtually identical, at least in terms of recommendations for use. This has mostly been the case since their development over 60 years ago. The concept, still often quoted, that they are 70-90% protective against laboratory-confirmed clinical influenza comes from multiple studies carried out with different preparations in the US military; studies which ended in 1969 [1]. During this period, there were only gradual advances in improved potency and purity of the vaccines, so that it was appropriate to consider them as being comparable. However, we are currently witnessing a change, which started slowly, but is now accelerating, in which very different types of vaccine are becoming available. This has already begun in some parts of the world, but will soon be universal. The process is being accelerated by questions concerning the actual effectiveness of the current vaccines in specific risk groups. In this paper, we will take a look at the developments in the formulation of the vaccine to address the needs that have been identified. We will also consider different strategies for vaccine use which might be applied to traditional or future vaccines to improve population protection.

Evaluation of seasonal influenza vaccination effectiveness based on antibody efficacy among the institutionalized elderly in Japan

Influenza vaccination efficacy was evaluated in 114 institutionalized elderly people in 2002/03. Strain A/H3N2 was isolated; 44 and 8 subjects had sudden-onset fever (> or = 37.8 degrees C) and kit-diagnosed influenza, respectively. Odds ratios adjusted for age, sex, comorbidity, and vaccine strain (OR(adj)) were determined using multiple logistic regression. Seroprotected patients (haemagglutination-inhibition antibody titre > or = 1:40) had lower incidence of fever (OR(adj), 0.35; 95% confidence interval [CI], 0.09-1.28) and kit-diagnosed influenza (OR(adj), 0.35; 95% CI, 0.03-4.64) than patients without seroprotection (antibody efficacy, approximately 65%). Seroprotective levels of vaccination-induced antibodies probably prevent influenza among the institutionalized elderly, although statistical significance could not be confirmed owing to the sample size.

Vaccines for preventing influenza in the elderly

BACKGROUND

Vaccines have been the main global weapon to minimise the impact of influenza in the elderly for the last four decades and are recommended worldwide for individuals aged 65 years or older. The primary goal of influenza vaccination in the elderly is to reduce the risk of complications among persons who are most vulnerable.

OBJECTIVES

To assess the effectiveness of vaccines in preventing influenza, influenza-like illness (ILI), hospital admissions, complications and mortality in the elderly. To identify and appraise comparative studies evaluating the effects of influenza vaccines in the elderly. To document types and frequency of adverse effects associated with influenza vaccines in the elderly.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which contains the Cochrane Acute Respiratory Infections (ARI) Group's Specialised Register (The Cochrane Library 2009, issue 4); MEDLINE (January 1966 to October Week 1 2009); EMBASE (1974 to October 2009) and Web of Science (1974 to October 2009).

SELECTION CRITERIA

Randomised controlled trials (RCTs), quasi-RCTs, cohort and case-control studies assessing efficacy against influenza (laboratory-confirmed cases) or effectiveness against influenza-like illness (ILI) or safety. Any influenza vaccine given independently, in any dose, preparation or time schedule, compared with placebo or with no intervention was considered.

DATA COLLECTION AND ANALYSIS

We grouped reports first according to the setting of the study (community or long-term care facilities) and then by level of viral circulation and vaccine matching. We further stratified by co-administration of pneumococcal polysaccharide vaccine (PPV) and by different types of influenza vaccines. We analysed the following outcomes: influenza, influenza-like illness, hospital admissions, complications and deaths.

MAIN RESULTS

We included 75 studies. Overall we identified 100 data sets. We identified one RCT assessing efficacy and effectiveness. Although this seemed to show an effect against influenza symptoms it was underpowered to detect any effect on complications (1348 participants). The remainder of our evidence base included non-RCTs. Due to the general low quality of non-RCTs and the likely presence of biases, which make interpretation of these data difficult and any firm conclusions potentially misleading, we were unable to reach clear conclusions about the effects of the vaccines in the elderly.

AUTHORS' CONCLUSIONS

The available evidence is of poor quality and provides no guidance regarding the safety, efficacy or effectiveness of influenza vaccines for people aged 65 years or older. To resolve the uncertainty, an adequately powered publicly-funded randomised, placebo-controlled trial run over several seasons should be undertaken.

Efficacy of live attenuated influenza vaccine in children against influenza B viruses by lineage and antigenic similarity

Seasonal influenza vaccines, including live attenuated influenza vaccine (LAIV), contain three vaccine strains (two type A and one type B). Ideally, the hemagglutinin antigens of the recommended vaccine strains are antigenically similar to epidemic wild-type strains; in actuality, the antigenic match between circulating and vaccine strains each year can vary significantly owing to intermittent genetic reassortment and continuous antigenic drift. For influenza B, antigenic relatedness is further complicated by the existence of two distinct lineages. Consequently, the influenza B vaccine component can be of a completely different antigenic lineage from the circulating epidemic strains. Using data from nine randomized clinical trials in young children (6 months to 6 years of age), vaccine efficacy of LAIV against influenza B strains was assessed across this spectrum of antigenic relatedness. In an integrated analysis, vaccine efficacy of two doses of LAIV in vaccine-naive children was 86% against B strains of the same lineage and closely matched to the vaccine strain, 55% against strains of the same lineage but antigenically drifted from the vaccine strain, and 31% against strains of the opposite B lineage and antigenically unrelated to the vaccine strain. These data provide a more accurate assessment of the protection provided by the current trivalent vaccine and highlight the need for vaccination strategies that provide enhanced protection against both lineages of influenza B such as a quadrivalent influenza vaccine.

New strategies are needed to improve the accuracy of influenza vaccine effectiveness estimates among seniors

OBJECTIVE

The magnitude of the benefit of influenza vaccine among elderly individuals has been recently debated. Existing vaccine effectiveness estimates derive primarily from observational studies, which may be biased. In this paper, we provide a methodological examination of the potential sources of bias in observational studies of influenza vaccine effectiveness in seniors and propose design and analysis strategies to reduce bias in future studies.

STUDY DESIGN AND SETTING

We draw parallels to bias documented in observational studies of therapies in other areas of medical research including pharmacoepidemiology, discuss reasons why existing adjustment methods in influenza studies may not adequately control for the bias, and evaluate statistical approaches that may yield more accurate estimation of influenza vaccine effectiveness.

RESULTS

There is strong evidence for the presence of bias in existing observational estimates of influenza vaccine effectiveness in the elderly and the failure of current adjustment methods to reduce bias.

CONCLUSION

Promising approaches for reducing bias include obtaining more accurate information on confounders, such as functional status, avoiding all-cause death in favor of outcomes, such as pneumonia or influenza-related pneumonia, and evaluating the extent to which bias is reduced by these and other methods using the 'control' period before influenza season.

Decreased immune responses to influenza vaccination in patients with heart failure

BACKGROUND

Heart failure (HF) patients are at risk for influenza despite widespread vaccination. Both humoral (antibody) and cytotoxic T-lymphocyte (CTL) responses are important for protection. We explored antibody- and CTL-mediated responses to the influenza vaccine in HF patients compared with healthy controls.

METHODS AND RESULTS

We studied 29 HF patients (9 ischemic, 20 nonischemic) stable on HF therapies and 17 healthy controls. Participants had phlebotomy before and after influenza vaccination. Antibody production was measured in serum by hemagglutination inhibition assay and CTL responses (via interferon [IFN]-gamma and interleukin [IL]-10 production) were measured in isolated peripheral blood mononuclear cells with enzyme-linked immunosorbent assay. CTL responses demonstrated increased IL-10 production in HF patients after vaccination (P = .002), but similar IFN-gamma responses to healthy controls. All participants demonstrated antibody seroprotection; groups had similar rates of seroconversion (P = NS). Antibody-mediated response to the newest vaccine antigen, H3N2, was reduced in HF (P = .009).

CONCLUSIONS

Patients with HF had higher vaccine induced IL-10 concentrations, suggesting a different CTL phenotype for vaccine responses. HF patients did not mount as vigorous of an antibody immune response to the newest vaccine viral strain compared with healthy individuals. These data suggest that immunologic memory may be important for vaccine protection in HF patients.

Influenza vaccination and risk of community-acquired pneumonia in immunocompetent elderly people: a population-based, nested case-control study

BACKGROUND

Pneumonia is a common complication of influenza infection in elderly individuals and could therefore potentially be prevented by influenza vaccination. In studies with data from administrative sources, vaccinated elderly people had a reduced risk of admission for pneumonia compared with unvaccinated seniors; however, these findings could have been biased by underlying differences in health between the groups. Furthermore, since most individuals with pneumonia are not treated in hospital, such studies should include both outpatient and inpatient events. We therefore assessed whether influenza vaccination is associated with a reduced risk of community-acquired pneumonia in immunocompetent elderly people after controlling for health status indicators.

METHODS

We did a population-based, nested case-control study in immunocompetent elderly people aged 65-94 years (cases and controls) enrolled in Group Health (a health maintenance organisation) during the 2000, 2001, and 2002 preinfluenza periods and influenza seasons. Cases were individuals with an episode of outpatient or inpatient community-acquired pneumonia (validated by review of medical records or chest radiograph reports). We randomly selected two age-matched and sex-matched controls for each case. The exposure of interest was influenza vaccination. We reviewed medical records to define potential confounders, including smoking history, presence and severity of lung and heart disease, and frailty indicators.

FINDINGS

1173 cases and 2346 controls were included in the study. After we adjusted for the presence and severity of comorbidities, as defined by chart review, influenza vaccination was not associated with a reduced risk of community-acquired pneumonia (odds ratio 0.92, 95% CI 0.77-1.10) during the influenza season.

INTERPRETATION

The effect of influenza vaccination on the risk of pneumonia in elderly people during influenza seasons might be less than previously estimated.

FUNDING

Group Health Center for Health Studies internal funds and Group Health Community Foundation fellowship grant.

Effect of social factors on winter hospital admission for respiratory disease: a case-control study of older people in the UK

BACKGROUND

Every winter, hospitals in the UK and other developed countries experience a surge in respiratory admissions. Ecological studies suggest that social circumstances may be an important determinant.

AIM

To establish the most important factors associated with winter hospital admissions among older people presenting with acute respiratory disease, especially the relative effect of social factors.

DESIGN OF STUDY

case-control study.

SETTING

Seventy-nine general practices in central England.

METHOD

Of a cohort of patients consulting medical services with lower respiratory tract infection or exacerbation of chronic respiratory disease, 157 hospitalised cases were compared to 639 controls. Social, medical, and other factors were examined by interview and GP records.

RESULTS

Measures of material deprivation were not significant risk factors for admission at either individual or area level, although social isolation (odds ratio [OR] 4.5; 95% confidence interval [CI] = 1.3 to 15.8) resulted in an increased risk of admission. The most important independent risk factor was the presence of chronic obstructive pulmonary disease (COPD; OR 4.0; 95% CI = 1.4 to 11.4), other chronic disease (OR 2.9; 95% CI = 1.2 to 7.0), or both (OR 6.7; 95% CI = 2.4 to 18.4). Being housebound was also an independent risk factor (OR 2.2; 95% CI = 1.0 to 4.8).

CONCLUSION

Socioeconomic factors had little relative effect compared with medical and functional factors. The most important was the presence of long-term medical conditions (especially COPD), being housebound, and having received two or more courses of oral steroid treatment in the previous year. This combination of factors could be used by primary medical services to identify older patients most vulnerable to winter admissions. Clinicians should ensure that patients with COPD are better supported to manage their condition.

A review of the factors involved in older people's decision making with regard to influenza vaccination: a literature review

AIMS AND OBJECTIVES

The aim of this paper was to develop an understanding of the factors involved in older people's decision making with regard to influenza vaccination to inform strategies to improve vaccine uptake and reduce morbidity and mortality.

BACKGROUND

Influenza is a major cause of morbidity and mortality world-wide. In the UK, it accounts for 3,000-6,000 deaths annually; 85% of these deaths are people aged 65 and over. Despite this, and the widespread and costly annual government campaigns, some older people at risk of influenza and the associated complications remain reluctant to take advantage of the offer of vaccination.

METHODS

A review of the English language literature referring to older people published between 1996 and 2005 was the method used. Inclusion and exclusion criteria were identified and applied.

RESULTS

The majority of the literature was quantitative in nature, investigating personal characteristics thought to be predictors of uptake, such as age, sex, co-morbidity, educational level, income and area of residence. However, there was little discussion of the possible reasons for the significance of these factors and conflict between findings was often evident, particularly between studies employing different methodologies. Other factors identified were prior experience, concerns about the vaccine, perceived risk and advice and information.

RELEVANCE TO CLINICAL PRACTICE

The wealth of demographic information available will be useful at a strategic level in targeting groups identified as being unlikely to accept vaccination. However, the promotion of person-centred ways of working that value the health beliefs, attitudes, perceptions and subjective experiences of older people is likely to be more successful during individual encounters designed to promote acceptance. Without more research in investigating these concepts, our understanding is inevitably limited.

The relationship between influenza vaccination and outpatient visits for upper respiratory infection by the elderly in Taiwan

OBJECTIVE

To evaluate the effect of influenza vaccination on the reduction of the risk of outpatient visits for upper respiratory infection (URI) among the elderly in Taiwan.

METHODS

The data for this observational study, consisting of 1729 people aged 65 years or older, were drawn from Taiwan's 2001 National Health Interview Survey. This survey data was then linked with National Health Insurance claim data for December 2001 to November 2002. Survival analysis of Cox proportional hazards model was performed to examine the risk of URI outpatient visits in elderly people vaccinated with the influenza vaccine and those not vaccinated during a year-long study period since the influenza season began. To adjust for potential self-selection bias, we used propensity score method to categorize individuals into two groups, based on the predicted probability of being vaccinated from a logistic regression of spatial random effect. Propensity score group 1 (PSG 1) were those with a predicted probability of being vaccinated lower than 0.5, and PSG 2 were those with a predicted probability of being vaccinated of 0.5 or higher.

RESULTS

The overall vaccination rate was 50%. Logistic regression showed the probability of being vaccinated was related to the number of outpatient visits for URI before the influenza season began (odds ratio (OR) 1.07; 95% confidence interval (CI) 1.04-1.10). Our first survival analysis showed that being vaccinated significantly reduced the risk of URI outpatient visits in PSG 2 during the 1-year study period (hazard ratio 0.89; 95% CI 0.81-0.97). Separate survival analysis showed that being vaccinated reduced the risk of URI outpatient visits for both PSG groups during the first 3 months of the study period.

CONCLUSION

Being vaccinated could reduce the risk of outpatient visits for URI among the elderly during the influenza season.

Influenza vaccine effectiveness among 50–64-year-old persons during a season of poor antigenic match between vaccine and circulating influenza virus strains: Colorado, United States, 2003–2004

During the 2003-2004 influenza season, we conducted a case-control study of influenza vaccine effectiveness (VE) among Colorado residents aged 50-64 years. Cases (n=330) were identified from laboratory-confirmed influenza reports to the Colorado Department of Public Health and Environment (CDPHE). Controls (n=1055) were recruited by random-digit dial telephone survey. VE was 60% (43-72%) and 48% (21-66%) among those without and with high-risk medical conditions, respectively. VE was 90% (68-97%) and 36% (0-63%) against influenza-related hospitalization for persons without and with high-risk conditions, respectively.

Prevention and control of influenza in persons with chronic obstructive pulmonary disease

Despite recommendations for annual vaccination against influenza, more than half of patients with chronic obstructive pulmonary disease (COPD) in developed countries do not receive this vaccine. Influenza is characterized by its potentially of causing epidemics and by excess morbidity and mortality in patients with COPD and other chronic medical conditions. Good evidence of the efficacy, effectiveness, and cost-effectiveness of influenza vaccination underlines the recommendation of use in patients with COPD. Influenza vaccination could reduce influenza-related complications and exacerbations in patients with COPD, therefore reducing hospitalizations and deaths. Each year, all persons with COPD should be vaccinated with the inactivated trivalent influenza vaccine containing the most frequent two influenza A viral strains and one influenza B viral strain detected in the influenza season of the previous year. To achieve a 100% vaccination rate in patients with COPD, all patients with COPD registered in health insurance companies and attended in health centers and specialized clinics should be vaccinated during the immunization period (October-December). Antiviral therapies could be used as an adjunct to vaccination and to reduce influenza transmission in outbreaks. Antiviral therapies could reduce the duration and complications of influenza when administered within two days of the onset of illness. Research is necessary for new antiviral therapies that could prevent influenza with cost-effectiveness similar to the influenza vaccine.

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.

Vaccines for preventing influenza in the elderly

BACKGROUND

Influenza vaccination of elderly individuals is recommended worldwide and has been targeted toward the elderly and those at serious risk of complications.

OBJECTIVES

Our aim was to review the evidence of efficacy, effectiveness and safety of influenza vaccines in individuals aged 65 years or older.

SEARCH STRATEGY

We searched the following databases on The Cochrane Library, the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Database of Systematic Reviews, and the Database of Abstracts of Reviews of Effectiveness (Issue 1, 2006); MEDLINE (January 1966 to March Week 3 2006); EMBASE (Dialog 1974 to 1979; SilverPlatter 1980 to December 2005); Biological Abstracts (SilverPlatter 1969 to December 2004); and Science Citation Index (Web of Science 1974 to December 2004).

SELECTION CRITERIA

We considered randomised, quasi-randomised, cohort and case-control studies assessing efficacy against influenza (laboratory-confirmed cases) or effectiveness against influenza-like illness (ILI) or safety. Any influenza vaccine given independently, in any dose, preparation or time schedule, compared with placebo or with no intervention was considered.

DATA COLLECTION AND ANALYSIS

We grouped reports first according to the setting of the study (community or long-term care facilities) and then by level of viral circulation and vaccine matching. We further stratified by co-administration of pneumococcal polysaccharide vaccine (PPV) and by different types of influenza vaccines. We analysed the following outcomes: influenza, influenza-like illness, hospital admissions, complications and deaths.

MAIN RESULTS

Sixty-four studies were included in the efficacy / effectiveness assessment, resulting in 96 data sets. In homes for elderly individuals (with good vaccine match and high viral circulation) the effectiveness of vaccines against ILI was 23% (6% to 36%) and non-significant against influenza (RR 1.04: 95% CI 0.43 to 2.51). We found no correlation between vaccine coverage and ILI attack rate. Well matched vaccines prevented pneumonia (VE 46%; 30% to 58%), hospital admission (VE 45%; 16% to 64%) and deaths from influenza or pneumonia (VE 42%, 17% to 59%). In elderly individuals living in the community, vaccines were not significantly effective against influenza (RR 0.19; 95% CI 0.02 to 2.01), ILI (RR 1.05: 95% CI 0.58 to 1.89), or pneumonia (RR 0.88; 95% CI 0.64 to 1.20). Well matched vaccines prevented hospital admission for influenza and pneumonia (VE 26%; 12% to 38%) and all-cause mortality (VE 42%; 24% to 55%). After adjustment for confounders, vaccine performance was improved for admissions to hospital for influenza or pneumonia (VE* 27%; 21% to 33%), respiratory diseases (VE* 22%; 15% to 28%) and cardiac disease (VE* 24%; 18% to 30%); and for all-cause mortality (VE* 47%; 39% to 54%). The public health safety profiles of the vaccines appear to be acceptable.

AUTHORS' CONCLUSIONS

In long-term care facilities, where vaccination is most effective against complications, the aims of the vaccination campaign are fulfilled, at least in part. However, according to reliable evidence the usefulness of vaccines in the community is modest. The apparent high effectiveness of the vaccines in preventing death from all causes may reflect a baseline imbalance in health status and other systematic differences in the two groups of participants.

Overcoming gaps in the management of asthma in older patients: new insights

Asthma is under-recognised and undertreated in older populations. This is not surprising, given that one-third of older people experience significant breathlessness. The differential diagnosis commonly includes asthma, chronic obstructive pulmonary disease (COPD), heart failure, malignancy, aspiration and infections. Because symptoms and signs of several cardiorespiratory diseases are nonspecific in older people and diseases commonly co-exist, investigations are important. A simple strategy for the investigation of breathlessness in older people should include a full blood count, chest radiograph, ECG, peak flow diary and/or spirometry with reversibility as a minimum. If there are major abnormalities on the ECG, an echocardiogram should also be performed. Diurnal variability in peak flow readings >or=20% or >or=15% reversibility in forced expiratory volume in 1 second, spontaneously or with treatment, support a diagnosis of asthma. Distinguishing asthma from COPD is important to allow appropriate management of disease based on aetiology, accurate prediction of treatment response, correct prognosis and appropriate management of the chest condition and co-morbidities. The two conditions are usually readily differentiated by clinical features, particularly age at onset, variability of symptoms and nocturnal symptoms in asthma, supported by the results of reversibility testing. Full lung function tests may not necessarily help in differentiating the two entities, although gas transfer factor is characteristically reduced in COPD and usually normal or high in asthma. Methacholine challenge tests previously mainly used in research are now also used widely and safely to confirm asthma in clinical settings. Interest in exhaled nitric oxide as a biomarker of airways inflammation is increasing as a noninvasive tool in the diagnosis and monitoring of asthma. Regular inhaled corticosteroids (ICS) are the mainstay of treatment of asthma. Even in mild disease in older adults, regular preventive treatment should be considered, given the poor perception of bronchoconstriction by older asthmatic patients. If symptoms persist despite ICS, addition of long-acting beta(2)-adrenoceptor agonists (LABA) should be considered. Addition of LABA to ICS improves asthma control and allows reduction in ICS dose. However, older people have been grossly under-represented in trials of LABA, many trials having excluded those >or=65 years of age. On meta-analysis, beta(2)-adrenoceptor agonists (both short acting and long acting) are associated with increased cardiovascular mortality and morbidity in asthma and COPD. While the evidence for excess cardiovascular mortality is stronger for short-acting beta(2)-adrenoceptor agonists, it would be prudent to exercise particular care in using beta(2)-adrenoceptor agonists (long acting and short acting) in those at risk of adverse cardiovascular outcomes, including older people. Regular review of cardiovascular status (and monitoring of serum potassium concentration) in patients taking beta(2)-adrenoceptor agonists is crucial. The response to LABA should be carefully monitored and alternative 'add-on' therapy such as leukotriene receptor antagonists (LRA) should be considered. LRA have fewer adverse effects and in individual cases may be more effective and appropriate than LABA. Long-term trials evaluating beta(2)-adrenoceptor agonists and other bronchodilator strategies are needed particularly in the elderly and in patients with cardiovascular co-morbidities. There is no evidence that addition of anticholinergics improves control of asthma further, although the role of long-acting anticholinergics in the prevention of disease progression is currently being researched. Older patients need to be taught good inhaler technique to improve delivery of medications to lungs, minimise adverse effects and reduce the need for oral corticosteroids. Nurse-led education programmes that include a written asthma self-management plan have the potential to improve outcomes.

Fatores associados à vacinação contra influenza em idosos em município do Sudeste do Brasil

OBJETIVO: Mesmo gratuita e disponível no Brasil desde 1999, a cobertura vacinal contra a influenza ainda é inadequada em diversos municípios do País. O objetivo da pesquisa foi estimar a cobertura vacinal e identificar fatores relacionados à vacinação contra a influenza em idosos. MÉTODOS: Realizou-se inquérito domiciliar em amostra aleatória sistemática (N=365) da população urbana maior de 60 anos em Botucatu, São Paulo. Foi aplicado modelo de regressão logística múltipla, cuja variável dependente foi ter sido vacinado em 2002. Foram testadas no modelo as covariáveis: sexo, idade, socioeconômicas (renda per capita, número de pessoas por cômodo, escolaridade, estado civil, ocupação, tempo de moradia), antecedentes mórbidos, de internação, hábito de fumar, sintomas respiratórios nos últimos 15 dias e atividades comunitárias (trabalho voluntário, atividades no bairro, igreja). RESULTADOS: Registrou-se cobertura vacinal de 63,2% (IC 95%: 58,3-68,2). Foi observado menor percentual de vacinados entre os idosos na faixa etária de 60 a 64 anos. As variáveis que se mostraram associadas à vacinação e permaneceram no modelo final foram: idade (OR=1,09 por ano; IC 95%: 1,06-1,13); hipertensão arterial (OR=1,92; IC 95%: 1,18-3,13); inserção em atividades na comunidade (OR=1,63; IC 95%: 1,01-2,65). A vacinação em portadores de doenças crônicas não atingiu níveis adequados conforme esperado para este grupo de risco, com exceção dos hipertensos. A participação em atividades comunitárias e sociais foi relacionada com o estado vacinal. CONCLUSÕES: Condições socioeconômicas, hábitos e idade não restringiram o acesso à campanha vacinal. Por outro lado, campanhas específicas, endereçadas a indivíduos da faixa de 60 a 64 anos, podem ampliar a cobertura da vacinação.

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.

Efficacy and effectiveness of influenza vaccines in elderly people: a systematic review

BACKGROUND

Influenza vaccination of elderly individuals is recommended worldwide. Our aim was to review the evidence of efficacy and effectiveness of influenza vaccines in individuals aged 65 years or older.

METHODS

We searched five electronic databases to December, 2004, in any language, for randomised (n=5), cohort (n=49), and case-control (n=10) studies, assessing efficacy against influenza (reduction in laboratory-confirmed cases) or effectiveness against influenza-like illness (reduction in symptomatic cases). We expressed vaccine efficacy or effectiveness as a proportion, using the formula VE=1-relative risk (RR) or VE*=1-odds ratio (OR). We analysed the following outcomes: influenza, influenza-like illness, hospital admissions, complications, and deaths.

FINDINGS

In homes for elderly individuals (with good vaccine match and high viral circulation) the effectiveness of vaccines against influenza-like illness was 23% (95% CI 6-36) and non-significant against influenza (RR 1.04, 0.43-2.51). Well matched vaccines prevented pneumonia (VE 46%, 30-58) and hospital admission (VE 45%, 16-64) for and deaths from influenza or pneumonia (VE 42%, 17-59), and reduced all-cause mortality (VE 60%, 23-79). In elderly individuals living in the community, vaccines were not significantly effective against influenza (RR 0.19, 0.02-2.01), influenza-like illness (RR 1.05, 0.58-1.89), or pneumonia (RR 0.88, 0.64-1.20). Well matched vaccines prevented hospital admission for influenza and pneumonia (VE 26%, 12-38) and all-cause mortality (VE 42%, 24-55). After adjustment for confounders, vaccine performance was improved for admissions to hospital for influenza or pneumonia (VE* 27%, 21-33), respiratory diseases (VE* 22%, 15-28), and cardiac disease (VE* 24%, 18-30), and for all-cause mortality (VE* 47%, 39-54).

INTERPRETATION

In long-term care facilities, where vaccination is most effective against complications, the aims of the vaccination campaign are fulfilled, at least in part. However, according to reliable evidence the usefulness of vaccines in the community is modest.

The impact of influenza on the health and health care utilisation of elderly people

Despite intensive research, influenza viruses still present one of the major causes of respiratory disease throughout the world. The elderly population and those individuals considered "at risk" due to presenting co-morbidity are especially vulnerable to influenza infection; this is evident from increased rates of morbidity and mortality in these populations during winter epidemic periods. Successful vaccination campaigns have targeted these groups over the last few years, providing protection to an increasing number of susceptible individuals. However, during periods of influenza virus activity there are still seasonal pressures put on both primary and secondary health care services. In the event of a serious influenza epidemic or pandemic, these burdens could jeopardise health care provision to at risk populations. In this report we discuss current issues surrounding the impact of influenza on the health care utilisation of elderly people.

Influenza Vaccination in the Elderly

Influenza causes substantial morbidity across the age spectrum. However, the elderly are especially vulnerable to the serious complications of influenza that might result in hospitalisation or death, and high rates of influenza-associated excess hospitalisation or death that exceed by several-fold the rates seen among most other age groups have consistently been observed in many countries and across many seasons. Thus, the elderly are included among the high priority groups for routine influenza vaccination by many national health authorities. Inactivated influenza virus vaccines are widely available across the globe and are safe and effective. Vaccination of elderly persons has been associated with significant reductions in hospitalisations for pneumonia and influenza as well as hospitalisations for other cardiopulmonary disorders and even cerebrovascular disease. Vaccination has also been associated with reductions in influenza-associated and all-cause mortality during influenza seasons. The benefits of vaccination extend not only to community-dwelling elderly but also to elderly who reside in nursing homes. Likewise, vaccination provides benefits to the very old and to elderly persons with underlying co-morbidities as well as to the healthy elderly. Despite the substantially increased risk for serious complications and impressive benefits from vaccination among the elderly, influenza vaccine utilisation remains below target rates for this group in nearly all countries. The need for improved prevention and control of influenza is recognised as a priority for the global community--both to reduce the morbidity and mortality associated with epidemic influenza and to prepare for the next pandemic. Enhancing vaccine delivery to elderly persons would represent important progress toward that goal.

Vaccination of high-risk patients against influenza: impact on primary care contact rates during epidemics. Analysis of routinely collected data

A general practice (GP) based retrospective cohort study was conducted to assess the effects of influenza vaccination on the primary care contact rate during influenza epidemics. Given the rising workload of family physicians, particularly due to ageing of the population, it is very relevant to know to whether influenza vaccination of high-risk patients reduces the contact rate during epidemics. No effect of vaccination was found on the contact rate of GP during a mild epidemic period. During a 'normal' influenza epidemic, the workload was reduced through fewer contacts by patients with cardiovascular or diabetic diseases. Epidemic periods severe enough to show contact rate reduction occurred approximately every other year.

A nested case-control study of influenza vaccination was a cost-effective alternative to a full cohort analysis

OBJECTIVE

In the absence of trial results that are applicable to the target population, nested case-control studies might be an alternative to full-cohort analysis. We compared relative and absolute estimates of associations in an influenza vaccine study using both designs.

STUDY DESIGN AND SETTING

Data from elderly persons enrolled during six consecutive influenza seasons were used (147,551 person-periods). The endpoints "hospitalization for pneumonia or influenza" (P&I) or "death" were used combined and separately to define three types of cases. Controls for the case-control samples were randomly selected from the remainder of the total cohort at different ratios (1:1 to 1:4). Logistic regression analysis was used to assess adjusted vaccine effectiveness (VE). Sampling fractions were used to determine the number needed to treat to prevent one outcome. Receiver-operator-curve analysis was conducted to estimate the area under the curve (AUC) as a measure of discriminative capacity of the prognostic model.

RESULTS

In all, 978 P and I hospitalizations and 1,339 deaths were observed. The adjusted estimates of relative estimates (VE, AUC) and their corresponding 95% confidence intervals were virtually the same using both study designs, notably when the case-control ratio was high (1:4).

CONCLUSION

A nested case-control design can provide valid and precise estimates of associations and is a cost-effective alternative for full-cohort analysis.

Internações por doenças respiratórias em idosos e a intervenção vacinal contra influenza no Estado de São Paulo

As doenças respiratórias, particularmente as pneumonias e gripes, são importante causa de internação e óbito entre os idosos. O objetivo deste estudo foi avaliar o comportamento da morbidade hospitalar por doenças respiratórias na população idosa do Estado de São Paulo, no período de 1995 a 2002, examinando-se a tendência das internações após a intervenção vacinal contra a influenza. Foram utilizadas as bases de dados de Autorizações de Internação Hospitalar do Ministério da Saúde. Os indicadores de morbidade, referentes às causas respiratórias selecionadas, foram: taxa de internação hospitalar por 1000 habitantes; proporção de internações por tais causas entre o total de internações; e razão entre internações mensais e o número de leitos de clínica médica disponíveis mensalmente. No Estado de São Paulo, observou-se mudança nos indicadores de morbidade após a vacinação, em ambos os sexos, com diferentes padrões entre as faixas etárias, sugerindo impacto positivo na prevenção de internações em idosos.

Influenza

Although most influenza infections are self-limited, few other diseases exert such a huge toll of suffering and economic loss. Despite the importance of influenza, there had been, until recently, little advance in its control since amantadine was licensed almost 40 years ago. During the past decade, evidence has accrued on the protection afforded by inactivated vaccines and the safety and efficacy in children of live influenza-virus vaccines. There have been many new developments in vaccine technology. Moreover, work on viral neuraminidase has led to the licensing of potent selective antiviral drugs, and economic decision modelling provides further justification for annual vaccination and a framework for the use of neuraminidase inhibitors. Progress has also been made on developing near-patient testing for influenza that may assist individual diagnosis or the recognition of widespread virus circulation, and so optimise clinical management. Despite these advances, the occurrence of avian H5N1, H9N2, and H7N7 influenza in human beings and the rapid global spread of severe acute respiratory syndrome are reminders of our vulnerability to an emerging pandemic. The contrast between recent cases of H5N1 infection, associated with high mortality, and the typically mild, self-limiting nature of human infections with avian H7N7 and H9N2 influenza shows the gaps in our understanding of molecular correlates of pathogenicity and underlines the need for continuing international research into pandemic influenza. Improvements in animal and human surveillance, new approaches to vaccination, and increasing use of vaccines and antiviral drugs to combat annual influenza outbreaks are essential to reduce the global toll of pandemic and interpandemic influenza.

A prospective, Internet-based study of the effectiveness and safety of influenza vaccination in the 2001–2002 influenza season

The effectiveness of the influenza vaccine used in the 2001-2002 influenza season in Japan was investigated in a large-scale, geographically widely distributed, Internet-based study. Data were collected from 8841 of 9902 subjects registered by 38 clinics prior to the start of influenza season. Subjects were categorized into three groups by vaccination regimen: unvaccinated, vaccinated once, and vaccinated twice. Efficacy was also analyzed for three age groups: 0-15, 16-64, and 65-104 years. Influenza-like illness (ILI) was diagnosed according to Ministry of Health (MWH, Labor and Welfare in Japan) criteria. Laboratory-confirmed influenza cases were analyzed separately. The respective vaccine efficacy in the 0-15 years group for the one- and two-dose regimens was 67.6 and 84.5% for ILI and 54.0 and 79.8% for laboratory-confirmed influenza. Influenza vaccination was also shown to be effective in subjects 16-64 years. Vaccine effectiveness was not able to be determined for the over 65 years group, probably due to an insufficient number of infected patients. These results suggest that influenza vaccination is effective for children and adults and that a two-dose regimen is superior to a single dose in children 0-15 years.

Conventional influenza vaccination is not associated with complications in working-age patients with asthma or chronic obstructive pulmonary disease

By using a nested case-control design, the authors studied the effectiveness of the influenza vaccine in reducing severe and fatal complications in 4,241 and 5,966 primary care, working-age patients aged 18-64 years who had asthma or chronic obstructive pulmonary disease during the 1998-1999 and 1999-2000 influenza epidemics in the Netherlands. Patients developing fatal or nonfatal exacerbations of lung disease, pneumonia, congestive heart failure, or myocardial infarction during either epidemic were considered cases. For each case, four age- and sex-matched controls were randomly sampled, and patient records were reviewed. Conditional logistic regression and propensity scores were used to assess vaccine effectiveness after adjustment for confounding factors. In seasons one and two, respectively, 87% (47/54) and 85% (171/202) of the cases and 74% (155/210) and 75% (575/766) of the controls had been vaccinated. After adjustments, vaccination was not associated with reductions in complications (season one: odds ratio = 0.95, 95% confidence interval (CI): 0.26, 3.48; season two: odds ratio = 1.07, 95% CI: 0.59, 1.96; pooled odds ratio = 1.07, 95% CI: 0.63, 1.80). Because influenza vaccination appeared not to be associated with a clinically relevant reduction in severe morbidity, other measures need to be explored.

Influenza vaccination and reduction in hospitalizations for cardiac disease and stroke among the elderly

BACKGROUND

Upper respiratory tract illnesses have been associated with an increased risk of ischemic heart disease and stroke. During two influenza seasons, we assessed the influence of vaccination against influenza on the risk of hospitalization for heart disease and stroke, hospitalization for pneumonia and influenza, and death from all causes.

METHODS

Cohorts of community-dwelling members of three large managed-care organizations who were at least 65 years old were studied during the 1998-1999 and 1999-2000 influenza seasons. Administrative and clinical data were used to evaluate outcomes, with multivariable logistic regression to control for base-line demographic and health characteristics of the subjects.

RESULTS

There were 140,055 subjects in the 1998-1999 cohort and 146,328 in the 1999-2000 cohort, of which 55.5 percent and 59.7 percent, respectively, were immunized. At base line, vaccinated subjects were on average sicker, having higher rates of most coexisting conditions, outpatient care, and prior hospitalization for pneumonia than unvaccinated subjects. Unvaccinated subjects, however, were more likely to have been given a prior diagnosis of dementia or stroke. Vaccination against influenza was associated with a reduction in the risk of hospitalization for cardiac disease (reduction of 19 percent during both seasons [P<0.001]), cerebrovascular disease (reduction of 16 percent during the 1998-1999 season [P<0.018] and 23 percent during the 1999-2000 season [P<0.001]), and pneumonia or influenza (reduction of 32 percent during the 1998-1999 season [P<0.001] and 29 percent during the 1999-2000 season [P<0.001]) and a reduction in the risk of death from all causes (reduction of 48 percent during the 1998-1999 season [P<0.001] and 50 percent during the 1999-2000 season [P<0.001]). In analyses according to age, the presence or absence of major medical conditions at base line, and study site, the findings were consistent across all subgroups.

CONCLUSIONS

In the elderly, vaccination against influenza is associated with reductions in the risk of hospitalization for heart disease, cerebrovascular disease, and pneumonia or influenza as well as the risk of death from all causes during influenza seasons. These findings highlight the benefits of vaccination and support efforts to increase the rates of vaccination among the elderly.

Design of the Dutch prevention of influenza, surveillance and management (PRISMA) study

Rationale and design of a study on the cost-effectiveness of the Dutch influenza vaccination campaign are described. During two influenza epidemics, about 75,000 primary care patients recommended for influenza vaccination are included. Cases have fatal or non-fatal influenza, pneumonia, otitis media, acute respiratory disease (ARD), heart failure, myocardial infarction, depression or diabetes dysregulation. Per case four controls are sampled, frequency matched on age and high-risk co-morbidity (<18 years, 18-64, >/=65 healthy, >/=65 with co-morbidity). Baseline and outcome data are retrieved from patient records. During the 1999-2000 influenza A epidemic 5891 (7.9%) high-risk children, 24,848 (33.2%) high-risk adults aged 18-64 years, 18,484 (24.7%) elderly with co-morbidity and 25,527 (34.1%) healthy elderly had been included. The mortality rate was 5.2 per 1000 and 2035 non-fatal outcome events were recorded (incidence rate 27.2/1000).

Influenza vaccinations: who needs them and when?

Influenza vaccination programmes should aim at reducing the burden from influenza among those who need it most. The primary aim of this literature review is to identify who should receive priority in influenza vaccination programmes. Risk factors for severe post-influenza complications include immune-related factors, such as ageing or the presence of immune-suppression, respiratory tract disease, proneness to exacerbation of concomitant high-risk disease, potential adverse effects associated with long-term drug use or residence in closed communities with high transmission rate. When given annually in autumn, inactivated trivalent influenza vaccines can reduce severe complications from influenza among persons aged 65 years or older by 30-60%. Among children aged less than 7 years, notably those with asthma, the occurrence of otitis media or acute respiratory disease is reduced by 20-75% with vaccination. In addition, vaccination of residents of long-term care facilities and their personnel leads to a 42% reduction in mortality among patients. However, uncertainty remains about whether influenza vaccination can reduce complications from influenza among the large group of older children and persons of working-age with high-risk disease. To further increase the impact of prevention strategies, the development and application of clinical prediction rules to estimate absolute risks of post-influenza complications should be studied in relation to optimal vaccine delivery strategies. Furthermore, adequately powered studies should be conducted to demonstrate possible effectiveness of vaccination in reducing post-influenza complications among older children and working-age adults.