Original Article
Effectiveness of Influenza Vaccine in the Community-Dwelling Elderly
N Engl J Med 2007; 357:1373-1381October 4, 2007
- Abstract
Background
Reliable estimates of the effectiveness of influenza vaccine among persons 65 years of age and older are important for informed vaccination policies and programs. Short-term studies may provide misleading pictures of long-term benefits, and residual confounding may have biased past results. This study examined the effectiveness of influenza vaccine in seniors over the long term while addressing potential bias and residual confounding in the results.
Methods
Data were pooled from 18 cohorts of community-dwelling elderly members of one U.S. health maintenance organization (HMO) for 1990–1991 through 1999–2000 and of two other HMOs for 1996–1997 through 1999–2000. Logistic regression was used to estimate the effectiveness of the vaccine for the prevention of hospitalization for pneumonia or influenza and death after adjustment for important covariates. Additional analyses explored for evidence of bias and the potential effect of residual confounding.
Results
There were 713,872 person-seasons of observation. Most high-risk medical conditions that were measured were more prevalent among vaccinated than among unvaccinated persons. Vaccination was associated with a 27% reduction in the risk of hospitalization for pneumonia or influenza (adjusted odds ratio, 0.73; 95% confidence interval [CI], 0.68 to 0.77) and a 48% reduction in the risk of death (adjusted odds ratio, 0.52; 95% CI, 0.50 to 0.55). Estimates were generally stable across age and risk subgroups. In the sensitivity analyses, we modeled the effect of a hypothetical unmeasured confounder that would have caused overestimation of vaccine effectiveness in the main analysis; vaccination was still associated with statistically significant — though lower — reductions in the risks of both hospitalization and death.
Conclusions
During 10 seasons, influenza vaccination was associated with significant reductions in the risk of hospitalization for pneumonia or influenza and in the risk of death among community-dwelling elderly persons. Vaccine delivery to this high-priority group should be improved.
Media in This Article
Figure 1
Risk of Outcomes According to Age and Risk Status for Unvaccinated and Vaccinated Groups.Figure 2
Effectiveness of the Influenza Vaccine in Reducing the Risk of Hospitalization for Pneumonia or Influenza (Panel A) and Death (Panel B).Article Activity
- Article
Influenza continues to be a major cause of illness and death, especially among the elderly. Each year, influenza and its complications are responsible for about 186,000 excess hospitalizations for respiratory and circulatory illness1 and 44,000 excess deaths from all causes2 in this high-risk group. Influenza vaccines are safe and effective, and the elderly are included among the high-priority groups targeted for annual vaccination.3
Reliable estimates of the benefits of vaccination are important for establishing informed policies regarding resource allocation for the delivery of immunizations and identifying the need for new vaccines and strategies for the prevention and control of influenza in this group.4 However, most studies assessing the effectiveness of influenza vaccination in the elderly have included one or only a few influenza seasons.5 Because of the variability of influenza from season to season, the results of these short-term studies — either favorable or unfavorable — might provide incomplete or misleading pictures about the benefits of vaccination over longer periods of time6; furthermore, heterogeneity between studies may limit the ability to pool results appropriately across studies.7
Because of ethical constraints imposed by recommendations that target the elderly for annual vaccination, most studies of the effectiveness of influenza vaccine in elderly persons have been observational studies and not randomized, controlled trials. Questions have been raised about the effects of potential bias and residual confounding on past estimates of vaccine effectiveness from these observational studies.8,9
In this study, we analyzed the effectiveness of influenza vaccination among 18 cohorts of community-dwelling elderly members of health maintenance organizations (HMOs) during 10 seasons. Our purpose was to provide a long-term view of the effectiveness of influenza vaccine while addressing potential bias and residual confounding.
Methods
We pooled subject-level data from 18 cohorts of elderly members of one U.S. HMO for the 1990–1991 through the 1999–2000 seasons and of two other U.S. HMOs for the 1996–1997 through the 1999–2000 seasons. Each cohort provided data for more than 20,000 person-seasons, for a total of 713,872 person-seasons during 10 seasons. The study authors were solely and independently responsible for the study design, the data analysis, the writing and preparation of all drafts of the manuscript, and the submission of the manuscript. The basic study design and methods have been described previously.10-13 The institutional research committees of the HMOs approved the project. Informed consent was not required.
Study Sites and Participants
The participating HMOs were HealthPartners in Minnesota and Wisconsin (1990–1991 through 1999–2000); Kaiser Permanente Northwest in the Portland, Oregon, and Vancouver, Washington, area (1996–1997 through 1999–2000); and Oxford Health Plans in New York City and surrounding counties (1996–1997 through 1999–2000). All noninstitutionalized members of the plans were included in that season's cohort if they were 65 years of age or older as of October 1, had been continuously enrolled in the plan for the preceding 12 months, were alive on the first day of the influenza season, and were either continuously enrolled or died during the outcome period. We selected these criteria to ensure adequate baseline and follow-up data and to reduce the potential for survivor bias.
Study Data
Data were extracted retrospectively from the administrative and clinical databases of the HMOs by the HMO research teams using standardized definitions that were consistent across the 10 seasons. Data elements included age, sex, baseline coexisting medical conditions (defined according to outpatient or inpatient International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes denoting heart disease, lung disease, diabetes, renal disease, hematologic or nonhematologic cancer, vasculitis or rheumatologic disease, dementia or stroke, and immune deficiency or organ transplantation), health care use during the previous 12 months (the number of hospitalizations and outpatient visits), year, site, and influenza-vaccination status. The study outcomes included hospitalization for pneumonia or influenza (ICD-9-CM codes 480 through 487) and death from any cause.
Influenza Seasons
Region-specific dates for the first and last influenza isolates reported to the Centers for Disease Control and Prevention defined the influenza seasons. Outcomes were included if they occurred during this period or, to capture delayed complications, within 2 weeks after the end of the influenza season.
Statistical Analysis
The baseline characteristics of vaccinated and unvaccinated subjects were compared with the use of the chi-square test and Student's t-test. Logistic regression (SPSS for Windows, version 13.0) was used to compare study outcomes between vaccinated and unvaccinated subjects after adjustment for covariates. The propensity score (the probability of being vaccinated given the observed covariates) was calculated for each subject and was included in the models with the use of strata based on quintiles of propensity score.14 Demographic characteristics, coexisting medical conditions, previous use of health care, site, and year were also included. Age (65 to 69 years, 70 to 79 years, 80 to 89 years, and 90 years and older) and number of outpatient visits (<4, 4 to 8, 9 to 15, and >15) were included as categorical variables. A similar model derived from and validated among vaccinated and unvaccinated cohorts from the three HMOs for the 1996–1997 and 1997–1998 seasons discriminated well between persons who did or did not enter the hospital or die during the influenza season.15 Vaccine effectiveness was estimated as a percentage: (1−adjusted odds ratio)×100.
We conducted subgroup analyses to explore for heterogeneity in levels of vaccine effectiveness and to divide the study population into more homogeneous strata that might reduce the effect of residual confounding or bias.16 The subgroups were defined by sex, age, risk status (high risk was defined as the presence of one or more major coexisting conditions at baseline, and low risk as the presence of no major coexisting conditions at baseline), propensity-score quintile, previous hospitalization, and previous use of outpatient care. To test for a healthy-vaccinee bias, we compared the risk of hospitalization for vaccinated and for unvaccinated persons during noninfluenza periods; data about hospitalization but not about mortality were available for the summer months of June through September after the 1998–1999 and 1999–2000 influenza seasons.
For our sensitivity analysis, we modeled how a hypothetical unmeasured confounder might have influenced our estimates of vaccine effectiveness. In our main analyses, vaccinated subjects appeared sicker than unvaccinated subjects, and we controlled for those measured differences. If an unmeasured confounder were also present so that persons with the confounder were less likely to be vaccinated but more likely to be hospitalized or die, then our main analyses would have overestimated vaccine effectiveness.17 Some examples of possible unmeasured confounders are race, income, and functional status. Limited data for two of the HMOs, however, suggest that the study populations were racially fairly homogeneous, with 85 to 90% of persons indicating that they were white (unpublished observations). Other investigators have reported that, after age, sex, and coexisting conditions have been controlled for, functional status is a stronger predictor of hospitalization or death among the elderly than is income.18 We therefore modeled our hypothetical confounder on the basis of published data about impaired functional status in the elderly.
On the basis of previous studies of functional status and the observed levels of association between important covariates with outcomes in our multivariable models, we estimated that plausible associations with vaccination and outcomes for a strong confounder would mean that persons with the confounder would be half as likely to be vaccinated19 and two to three times as likely to be hospitalized or die18,20-22 as would persons without the confounder. We varied the prevalence of the confounder from 20 to 60%.23 The method of Lin et al.24 was used to quantify the effect of the hypothetical confounder on our estimates of vaccine effectiveness. All reported P values are two-sided and were not adjusted for multiple testing.
Results
There were 713,872 person-seasons of observation. Vaccinated subjects were slightly older and had higher prevalence rates of all the baseline medical conditions except dementia or stroke (Table 1Table 1
Baseline Characteristics of the Study Subjects.).The predominant circulating virus strains for the 10 influenza seasons were type A/H3N2 for 6 seasons (1991–1992, 1993–1994, 1996–1997, 1997–1998, 1998–1999, and 1999-2000), type B for 1 season (1990–1991), mixed A/H3N2 and B for 2 seasons (1992–1993 and 1994–1995), and mixed A/H3N2 and A/H1N1 for 1 season (1995–1996).1,2 The vaccine–virus antigenic match was good to excellent in all seasons except 1992–1993 and 1997–1998, when the circulating A/H3N2 strains represented drifted variants.10,12
During the 10 influenza seasons, there were 4599 hospitalizations for pneumonia or influenza and 8796 deaths. The observed hospitalization rates for unvaccinated and for vaccinated participants were, on average, 0.7% and 0.6% per season, respectively, with corresponding death rates of 1.6% and 1.0% per season. Increasing age and the presence of one or more high-risk medical conditions at baseline were the strongest predictors of the risk of hospitalization or death in our models, with patterns of increasing risk being virtually identical for vaccinated and for unvaccinated persons (Figure 1Figure 1
Risk of Outcomes According to Age and Risk Status for Unvaccinated and Vaccinated Groups.).Influenza vaccination was associated on average with substantial reductions in hospitalizations for pneumonia and for influenza (vaccine effectiveness, 27%; adjusted odds ratio, 0.73; 95% confidence interval [CI], 0.68 to 0.77) and in death (vaccine effectiveness, 48%; adjusted odds ratio, 0.52; 95% CI, 0.50 to 0.55). Estimates varied from season to season and across the 18 cohorts (Figure 2Figure 2
Effectiveness of the Influenza Vaccine in Reducing the Risk of Hospitalization for Pneumonia or Influenza (Panel A) and Death (Panel B).). In the two seasons with a poor match between the vaccine and the virus strain, vaccine effectiveness was lower for reducing death (in seasons with a poor match, vaccine effectiveness was 37% [adjusted odds ratio, 0.63; 95% CI, 0.57 to 0.69]; in seasons with a good match, vaccine effectiveness was 52% [adjusted odds ratio, 0.48; 95% CI, 0.46 to 0.51]) but not for reducing hospitalization. Our multivariable regression models showed good to excellent discrimination, with C statistics of 0.76 (95% CI, 0.75 to 0.77) for hospitalization and 0.81 (95% CI, 0.80 to 0.81) for death.Estimates of vaccine effectiveness suggested clinically significant benefits across the subgroups (Figure 3Figure 3
Results of the Subgroup Analyses Assessing Vaccine Effectiveness in Reducing the Risk of Hospitalization (Panel A) and Death (Panel B).). There was, however, evidence for interaction between vaccination and high-risk status for hospitalization (P=0.004) and between vaccination and sex (P=0.03) and outpatient visits (P=0.03) for death. All other P values for interaction between vaccination and subgroup variables were greater than 0.05. Our analysis for evidence of a healthy-vaccinee bias was negative; during the two noninfluenza periods for which we had information, vaccinated and unvaccinated persons had similar risks of hospitalization (for June through September 1999, the adjusted odds ratio was 1.0 [95% CI, 0.78 to 1.28]; for June through September 2000, the adjusted odds ratio was 0.94 [95% CI, 0.74 to 1.19]).The sensitivity analysis shows how our estimates of vaccine effectiveness might have been influenced by residual confounding (Table 2Table 2
Sensitivity Analysis to Quantify the Effects of a Hypothetical Unmeasured Confounder on the Study Results.). With increasing prevalence of the confounder and with increasing risk of an outcome because of the confounder, estimates of vaccine effectiveness were incrementally lower though still significant. In the most extreme scenario that we evaluated, at a prevalence of 60% and an increased risk by a factor of three of an outcome, the estimates of vaccine effectiveness were reduced to 7% for hospitalization and 33% for death.Discussion
In this study, influenza vaccination of community-dwelling elderly persons during 10 seasons was associated with substantial reductions in hospitalizations for pneumonia or influenza and in death. By pooling patient-level data from 18 cohorts spanning the decade of the 1990s and including 713,872 person-seasons of observation, we have provided an important perspective on the benefits of vaccination among the elderly. We documented both the year-to-year variability that can be seen and the average long-term level of benefit from vaccination. Previous case–control and cohort studies from other populations and countries have also demonstrated benefits of vaccination in elderly populations.5,6 However, the limitations of studies based on a single or just a few influenza seasons, because of the substantial variability from year to year in circulating viruses and in antigenic match between circulating viruses and vaccine strains, and the challenges associated with attempts to pool results from heterogeneous studies in the absence of patient-level data6,7 have been acknowledged. Our study during 10 consecutive seasons attempts to overcome these limitations.
The large number of subjects in our data set permitted considerable precision in our estimates, which showed substantial benefits across multiple subgroups, a result suggesting that vaccination benefits probably extend to a broad spectrum of elderly persons. We also included subjects from three geographically diverse HMOs to enhance the likelihood that our study population would be representative of other HMO populations across the country. However, elderly enrollees in HMOs may differ from elderly persons without HMO coverage in important ways, including race, income, functional status, and urban versus nonurban residence,25 and caution should be used in generalizing our results to other groups.
In addition, our study was not designed to evaluate levels of vaccine effectiveness among the frailest elderly, such as those living in nursing homes. The elderly may have impaired humoral26 and cell-mediated27,28 immune responses to influenza vaccines. Institutionalized and other frail, elderly persons may be especially likely to exhibit such impaired immune responses,29,30 and therefore the levels of vaccine effectiveness in this population may be lower than those we have reported for the community-dwelling elderly.
Inactivated influenza vaccines are most effective when there is a good match between circulating viruses and vaccine strains; protection may also be substantial, though sometimes lower, during years with a poor match among healthy young adults,31,32 healthy adults and adults at high risk aged 50 through 64 years,33 and institutionalized elderly persons.34 Our findings are similar. During the two seasons with a poor match in our study, vaccination was associated with significant reductions in hospitalization and death, although the reduction in the risk of death was smaller than it was during the seasons with a good match.
Our results provide useful information on the benefits that elderly persons may receive from vaccination. How these results might relate to population-level trends is unclear. For example, influenza-attributable excess mortality rates in the United States have not declined to the degree that might be expected in light of increasing vaccination rates during the 1980s and the early 1990s.35 However, nation-level data do not include the risk profile or vaccination status of those who have died. Critical information is therefore lacking, making it difficult to estimate what the expected excess mortality rates would be if vaccination rates were 0%, what benefits have already been realized given current patterns of vaccine use, and what additional benefits might be realized with more effective vaccine delivery. Because of the large geographic variations in vaccine delivery in the United States, as well as disparities in vaccination rates according to race and ethnic group,36 the aging of the population,2 and the increasing numbers of elderly persons with high-risk conditions37,38 for whom the risk of dying increases exponentially, attempts to correlate population-level trends with individual levels of protection due to vaccination or vice versa will be susceptible to many pitfalls, including the ecologic fallacy.39
This study has several limitations. Because this was an observational study, we adjusted for important covariates in our analytic models. These models discriminated well between persons who did and those who did not become hospitalized or die. Our inclusion criteria were designed to minimize the possibility of survivor bias, and we did not find evidence for a healthy-vaccinee effect in our analyses. Nevertheless, residual confounding may have influenced our results, and our sensitivity analyses indicate how our estimates of vaccine effectiveness would be lower, though still significant, after adjustment for the effect of a strong hypothetical unmeasured confounder. Misclassification of vaccination status may also have occurred; the most likely cause of misclassification would have been a failure to record receipt of vaccine. However, at one of the HMOs, more than 90% of members at high risk who were vaccinated received the vaccine at a health plan site.40 Furthermore, agreement between medical records and computerized databases has been excellent, with more than 95% agreement at two of the study sites.12 Even if substantial misclassification occurred, it probably would have biased the results toward the null hypothesis.
Achieving optimal success in preventing and controlling influenza among the elderly may require more immunogenic vaccines and new strategies that induce greater levels of herd immunity and thereby interrupt influenza transmission in communities. More effective vaccines for the elderly are under development but have not yet been approved for use in the United States. Vaccination of children in the United States has been associated with reductions in illness in households41 and in the community,42 and in Japan with lower mortality rates among the elderly.43 However, these studies are not conclusive,44,45 and additional research is needed to define the benefits among the elderly that might be realized from vaccinating children. In the meantime, vaccination rates of elderly persons remain stagnant and well below the 2010 goal of 90%.3 Even as we wait for new vaccines and new strategies, patients, their health care providers, and policymakers should renew efforts to improve the delivery of current influenza vaccines to this high-priority group. Hospitalizations and deaths will be prevented if we can succeed.
Supported by the National Vaccine Program Office and the Centers for Disease Control and Prevention (CDC) through an agreement with the American Association of Health Plans, for the obtaining of the original data for 1996–1997 through 1999–2000 from HealthPartners in Minnesota and Wisconsin, Kaiser Permanente Northwest in the Portland, Oregon, and Vancouver, Washington, area, and Oxford Health Plans in New York City and surrounding counties; by the HealthPartners Research Foundation and Connaught Laboratories for the obtaining of the original data for 1990–1991 through 1995–1996 from HealthPartners; in part by the Center for Chronic Disease Outcomes Research at the Minneapolis VA Medical Center (to Dr. Nelson) for analysis of data for the data-pooling project; and by a grant (916.56.109) from the Netherlands Scientific Organization (to Dr. Hak).
Dr. Nichol reports serving as a consultant to or as a member of medical advisory boards of Sanofi Pasteur, MedImmune, GlaxoSmithKline, and Novartis and receiving grant support from Sanofi Pasteur and GlaxoSmithKline; and Dr. Nordin, receiving grant support from Sanofi Pasteur and the CDC. No other potential conflict of interest relevant to this article was reported.
Source Information
From the Medicine Service and Center for Chronic Disease Outcomes Research, Minneapolis Veterans Affairs Medical Center and University of Minnesota, Minneapolis (K.L.N., D.B.N.); the HealthPartners Research Foundation, Minneapolis (J.D.N.); Kaiser Permanente Northwest, Portland, OR (J.P.M.); and the Julius Center for Health Services and Primary Care, University Medical Center, Utrecht, the Netherlands (E.H.).
Address reprint requests to Dr. Nichol at Medicine Service (111), VA Medical Center, 1 Veterans Dr., Minneapolis, MN 55417, or at nicho014@umn.edu.
- References
References
1
Thompson WW ,Shay DK ,Weintraub E , et al. Influenza-associated hospitalizations in the United States. JAMA 2004;292:1333-1340
CrossRef | Web of Science | Medline2
Thompson WW ,Shay DK ,Weintraub E , et al. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA 2003;289:179-186
CrossRef | Web of Science | Medline3
Advisory Committee on Immunization Practices
Medline4
Schwartz B ,Hinman A ,Abramson J , et al. Universal influenza vaccination in the United States: are we ready? Report of a meeting. J Infect Dis 2006;194:Suppl 2:S147-S154
CrossRef | Web of Science | Medline5
Nichol KL . Influenza vaccination in the elderly: impact on hospitalisation and mortality. Drugs Aging 2005;22:495-515
CrossRef | Web of Science | Medline6
Jefferson T ,Rivetti D ,Rivetti A ,Rudin M ,Di Pietrantonj C ,Demicheli V . Efficacy and effectiveness of influenza vaccines in elderly people: a systematic review. Lancet 2005;366:1165-1174[Erratum, Lancet 2006;367:986.]
CrossRef | Web of Science | Medline7
Jacobson RM ,Targonski PV ,Poland GA . Meta-analyses in vaccinology. Vaccine 2007;25:3153-3159
CrossRef | Web of Science | Medline8
Glezen WP ,Simonsen L . Benefits of influenza vaccine in US elderly -- new studies raise questions. Int J Epidemiol 2006;35:352-353
CrossRef | Web of Science | Medline9
Jefferson T . Influenza vaccination: policy versus evidence. BMJ 2006;333:912-915
CrossRef | Web of Science | Medline10
Nichol KL ,Margolis KL ,Wuorenma J ,Von Sternberg T . The efficacy and cost effectiveness of vaccination against influenza among elderly persons living in the community. N Engl J Med 1994;331:778-784
Full Text | Web of Science | Medline11
Nichol KL ,Wuorenma J ,Von Sternberg T . Benefits of influenza vaccination for low-, intermediate-, and high-risk senior citizens. Arch Intern Med 1998;158:1769-1776
CrossRef | Web of Science | Medline12
Nordin J ,Mullooly J ,Poblete S , et al. Influenza vaccine effectiveness in preventing hospitalizations and deaths in persons 65 years or older in Minnesota, New York, and Oregon: data from 3 health plans. J Infect Dis 2001;184:665-670
CrossRef | Web of Science | Medline13
Nichol KL ,Nordin J ,Mullooly J ,Lask R ,Fillbrandt K ,Iwane M . Influenza vaccination and reduction in hospitalizations for cardiac disease and stroke among the elderly. N Engl J Med 2003;348:1322-1332
Full Text | Web of Science | Medline14
Rubin DB . Estimating causal effects from large data sets using propensity scores. Ann Intern Med 1997;127:757-763
Web of Science | Medline15
Hak E ,Wei F ,Nordin J ,Mullooly J ,Poblete S ,Nichol KL . Development and validation of a clinical prediction rule for hospitalization due to pneumonia or influenza or death during influenza epidemics among community-dwelling elderly persons. J Infect Dis 2004;189:450-458
CrossRef | Web of Science | Medline16
Hak E ,Verheij TJ ,Grobbee DE ,Nichol KL ,Hoes AW . Confounding by indication in non-experimental evaluation of vaccine effectiveness: the example of prevention of influenza complications. J Epidemiol Community Health 2002;56:951-955
CrossRef | Web of Science | Medline17
Hak E ,Hoes AW ,Nordin J ,Nichol KL . Benefits of influenza vaccine in US elderly -- appreciating issues of confounding bias and precision. Int J Epidemiol 2006;35:800-802
CrossRef | Web of Science | Medline18
Mayo NE ,Nadeau L ,Levesque L ,Miller S ,Poissant L ,Tamblyn R . Does the addition of functional status indicators to case-mix adjustment indices improve prediction of hospitalization, institutionalization, and death in the elderly? Med Care 2005;43:1194-1202
CrossRef | Web of Science | Medline19
Jackson LA ,Nelson JC ,Benson P , et al. Functional status is a confounder of the association of influenza vaccine and risk of all cause mortality in seniors. Int J Epidemiol 2006;35:345-352
CrossRef | Web of Science | Medline20
Walter LC ,Brand RJ ,Counsell SR , et al. Development and validation of a prognostic index for 1-year mortality in older adults after hospitalization. JAMA 2001;285:2987-2994
CrossRef | Web of Science | Medline21
Carey EC ,Walter LC ,Lindquist K ,Covinsky KE . Development and validation of a functional morbidity index to predict mortality in community-dwelling elders. J Gen Intern Med 2004;19:1027-1033
CrossRef | Web of Science | Medline22
Lee SJ ,Linkdquist K ,Segal MR ,Covinsky KE . Development and validation of a prognostic index for 4-year mortality in older adults. JAMA 2006;295:801-808
CrossRef | Web of Science | Medline23
Lethbridge-Cejku M, Rose D, Vickerie J. Summary health statistics for US adults: National Health Interview Survey, 2004. Vital and health statistics. Series 10. No. 228. Washington, DC: Government Printing Office, 2006:table 19. (Accessed September 7, 2007, at http://www.cdc.gov/nchs/data/series/sr_10/sr10_228.pdf.)
24
Lin DY ,Psaty BM ,Kronmal RA . Assessing the sensitivity of regression results to unmeasured confounders in observational studies. Biometrics 1998;54:948-963
CrossRef | Web of Science | Medline25
Banthin JS, Taylor AK. Medical Expenditure Panel Survey — research findings #15: HMO enrollment in the United States: estimates based on household reports, 1996. Rockville, MD: Agency for Healthcare Research and Policy. (Accessed September 7, 2007, at http://www.meps.ahrq.gov/mepsweb/data_files/publications/rf15/rf15.shtml.)
26
Goodwin K ,Viboud C ,Simonsen L . Antibody response to influenza vaccination in the elderly: a quantitative review. Vaccine 2006;24:1159-1169
CrossRef | Web of Science | Medline27
McElhaney JE . The unmet need in the elderly: designing new influenza vaccines for older adults. Vaccine 2005;23:Suppl 1:S10-S25
CrossRef | Web of Science | Medline28
Targonski PV ,Jacobson RM ,Poland GA . Immunosenescence: role and measurement in influenza vaccine response among the elderly. Vaccine 2007;25:3066-3069
CrossRef | Web of Science | Medline29
Gross PA ,Quinnan GV Jr ,Weksler ME ,Setia U ,Douglas RG Jr . Relation of chronic disease and immune response to influenza vaccine in the elderly. Vaccine 1989;7:303-308
CrossRef | Web of Science | Medline30
Fulop T Jr ,Wagner JR ,Khalil A ,Weber J ,Trottier L ,Payette H . Relationship between the response to influenza vaccination and the nutritional status in institutionalized elderly subjects. J Gerontol A Biol Sci Med Sci 1999;54:M59-M64
CrossRef | Web of Science | Medline31
Jefferson T ,Rivetti D ,Di Pietrantonj C ,Rivetti A ,Demicheli V . Vaccines for preventing influenza in healthy adults. Cochrane Database Syst Rev 2007;2:CD001269-CD001269
Medline32
Ohmit SE ,Victor JC ,Rotthoff JR , et al. Prevention of antigenically drifted influenza by inactivated and live attenuated vaccines. N Engl J Med 2006;355:2513-2522
Full Text | Web of Science | Medline33
Herrera GA ,Iwane MK ,Cortese M , et al. 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. Vaccine 2007;25:154-160
CrossRef | Web of Science | Medline34
Gross PA ,Hermogenes AW ,Sacks HS ,Lau J ,Levandowski RA . The efficacy of influenza vaccine in elderly persons: a meta-analysis and review of the literature. Ann Intern Med 1995;123:518-527
Web of Science | Medline35
Simonsen L ,Reichert TA ,Viboud C ,Blackwelder WC ,Taylor RJ ,Miller MA . Impact of influenza vaccination on seasonal mortality in the US elderly population. Arch Intern Med 2005;165:265-272
CrossRef | Web of Science | Medline36
Racial/ethnic disparities in influenza and pneumococcal vaccination levels among persons aged > or =65 years -- United States, 1989-2001. MMWR Morb Mortal Wkly Rep 2003;52:958-962
Medline37
Fry AM ,Shay DK ,Holman RC ,Curns AT ,Angerson LJ . Trends in hospitalizations for pneumonia among persons aged 65 years or older in the United States, 1988-2002. JAMA 2005;294:2712-2719
CrossRef | Web of Science | Medline38
Mokdad AH ,Ford ES ,Bowman BA , et al. Diabetes trends in the US: 1990-1998. Diabetes Care 2000;23:1278-1283
CrossRef | Web of Science | Medline39
Morgenstern H . Ecologic studies in epidemiology: concepts, principles, and methods. Annu Rev Public Health 1995;16:61-81
CrossRef | Web of Science | Medline40
Mac Donald R ,Baken L ,Nelson A ,Nichol KL . Validation of self-report of influenza and pneumococcal vaccination status in elderly outpatients. Am J Prev Med 1999;16:173-177
CrossRef | Web of Science | Medline41
King JC ,Stoddard JJ ,Gaglani M , et al. Effectiveness of school-based influenza vaccination. N Engl J Med 2006;355:2523-2532
Full Text | Web of Science | Medline42
Piedra PA ,Gaglani MJ ,Kozinetz CA , et al. Herd immunity in adults against influenza-related illnesses with the use of the trivalent-live attenuated influenza vaccine (CAIV-T) in children. Vaccine 2005;23:1540-1548
CrossRef | Web of Science | Medline43
Reichert TA ,Sugaya N ,Fedson DS ,Glezen WP ,Simonsen L ,Tashiro M . The Japanese experience with vaccinating schoolchildren against influenza. N Engl J Med 2001;344:889-896
Full Text | Web of Science | Medline44
Jordan R ,Connock M ,Albon E , et al. Universal vaccination of children against influenza: are there indirect benefits to the community? A systematic review of the evidence. Vaccine 2006;24:1047-1062
CrossRef | Web of Science | Medline45
Fukuda K ,Kieny MP . Different approaches to influenza vaccination. N Engl J Med 2006;355:2586-2587
Full Text | Web of Science | Medline
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Janet E. McElhaney, Xin Zhou, H. Keipp Talbot, Ernst Soethout, R. Chris Bleackley, David Granville, Graham Pawelec. (2012) The unmet need in the elderly: How immunosenescence, CMV infection, co-morbidities and frailty are a challenge for the development of more effective influenza vaccines. Vaccine
CrossRef6
A. Rodríguez, L. Álvarez-Rocha, J.M. Sirvent, R. Zaragoza, M. Nieto, A. Arenzana, P. Luque, L. Socías, M. Martín, D. Navarro, J. Camarena, L. Lorente, S. Trefler, L. Vidaur, J. Solé-Violán, F. Barcenilla, A. Pobo, J. Vallés, C. Ferri, I. Martín-Loeches, E. Díaz, D. López, M.J. López-Pueyo, F. Gordo, F. del Nogal, A. Marqués, S. Tormo, M.P. Fuset, F. Pérez, J. Bonastre, B. Suberviola, E. Navas, C. León. (2012) Recomendaciones del Grupo de Trabajo Enfermedades Infecciosas (GTEI) de la Sociedad Española de Medicina Intensiva, Crítica y Unidades Coronarias (SEMICYUC) y el Grupo de Estudio de Infecciones en el Paciente Crítico (GEIPC) de la Sociedad Española de Enfermedades Infecciosas y Microbiología clínica (SEIMC) para el diagnóstico y tratamiento de la gripe A/H1N1 en pacientes adultos graves hospitalizados en las Unidades de Cuidados Intensivos. Medicina Intensiva
CrossRef7
Robert B. Penfold, Donna Rusinak, Tracy A. Lieu, Abigail Shefer, Mark Messonnier, Grace M. Lee. (2011) Financing and systems barriers to seasonal influenza vaccine delivery in community settings. Vaccine 29:52, 9632-9639
CrossRef8
J. M. Ferdinands, D. K. Shay. (2011) Magnitude of Potential Biases in a Simulated Case-Control Study of the Effectiveness of Influenza Vaccination. Clinical Infectious Diseases
CrossRef9
Weiping Cao, Jin Hyang Kim, Tatiana Chirkova, Adrian J Reber, Renata Biber, David K Shay, Suryaprakash Sambhara. (2011) Improving immunogenicity and effectiveness of influenza vaccine in older adults. Expert Review of Vaccines 10:11, 1529-1537
CrossRef10
Kirsten Schneider-Ohrum, Brendan M. Giles, Heather K. Weirback, Brianne L. Williams, Dilhari R. DeAlmeida, Ted M. Ross. (2011) Adjuvants that stimulate TLR3 or NLPR3 pathways enhance the efficiency of influenza virus-like particle vaccines in aged mice. Vaccine 29:48, 9081-9092
CrossRef11
Barbara Michiels, Frans Govaerts, Roy Remmen, Etienne Vermeire, Samuel Coenen. (2011) A systematic review of the evidence on the effectiveness and risks of inactivated influenza vaccines in different target groups. Vaccine 29:49, 9159-9170
CrossRef12
Bruce M. Psaty. (2011) Conducting Comparative Effectiveness Research on Medications: The Views of a Practicing Epidemiologist from the Other Washington. Value in Health
CrossRef13
Seymour Katz, Darrell S Pardi. (2011) Inflammatory Bowel Disease of the Elderly: Frequently Asked Questions (FAQs). The American Journal of Gastroenterology 106:11, 1889-1897
CrossRef14
A. Friedl, C. Aegerter, E. Saner, D. Meier, J. H. Beer. (2011) An intensive 5-year-long influenza vaccination campaign is effective among doctors but not nurses. Infection
CrossRef15
O. YU, J. C. NELSON, L. BOUNDS, L. A. JACKSON. (2011) Classification algorithms to improve the accuracy of identifying patients hospitalized with community-acquired pneumonia using administrative data. Epidemiology and Infection 139:09, 1296-1306
CrossRef16
S. Augustine, R. A. Bonomo. (2011) Taking stock of infections and antibiotic resistance in the elderly and long-term care facilities: A survey of existingand upcoming challenges. European Journal of Microbiology and Immunology 1:3, 190-197
CrossRef17
Eelko Hak. (2011) Influenza vaccination in young children. The Lancet Infectious Diseases 11:9, 656
CrossRef18
Michael L. Jackson, Jennifer C. Nelson, Lisa A. Jackson. (2011) Why do covariates defined by International Classification of Diseases codes fail to remove confounding in pharmacoepidemiologic studies among seniors?. Pharmacoepidemiology and Drug Safety 20:8, 858-865
CrossRef19
Cristina Rodríguez-Rieiro, Valentín Hernández-Barrera, Pilar Carrasco-Garrido, Ana Lopez de Andres, Rodrigo Jiménez-García. (2011) Vaccination against 2008/2009 and 2009/2010 seasonal influenza in Spain: Coverage among high risk subjects, HCWs, immigrants and time trends from the 2005/2006 campaign. Vaccine 29:35, 6029-6034
CrossRef20
Jesús Castilla, Julio Morán, Víctor Martínez-Artola, Mirian Fernández-Alonso, Marcela Guevara, Manuel García Cenoz, Gabriel Reina, Nerea Alvarez, Maite Arriazu, Fernando Elía, Esther Salcedo, Aurelio Barricarte. (2011) Effectiveness of the monovalent influenza A(H1N1)2009 vaccine in Navarre, Spain, 2009–2010: Cohort and case-control study. Vaccine 29:35, 5919-5924
CrossRef21
Adriana Manzur, Conchita Izquierdo, Laura Ruiz, Dolores Sousa, Jose-María Bayas, Jose-Miguel Celorrio, Wenceslao Varona, Manel Nebot, Lluis Salleras, Angela Domínguez, Jordi Carratalà, . (2011) Influence of Prior Pneumococcal and Influenza Vaccination on Outcomes of Older Adults with Community-Acquired Pneumonia. Journal of the American Geriatrics Societyno-no
CrossRef22
Xu Yao, Robert G. Hamilton, Nan-ping Weng, Qian-Li Xue, Jay H. Bream, Huifen Li, Jing Tian, Shu-Hui Yeh, Barbara Resnick, Xiyan Xu, Jeremy Walston, Linda P. Fried, Sean X. Leng. (2011) Frailty is associated with impairment of vaccine-induced antibody response and increase in post-vaccination influenza infection in community-dwelling older adults. Vaccine 29:31, 5015-5021
CrossRef23
Janet E. McElhaney. (2011) Influenza vaccine responses in older adults. Ageing Research Reviews 10:3, 379-388
CrossRef24
Pierre-Olivier Lang, Sheila Govind, Wayne A. Mitchell, Claire-Anne Siegrist, Richard Aspinall. (2011) Vaccine effectiveness in older individuals: What has been learned from the influenza-vaccine experience. Ageing Research Reviews 10:3, 389-395
CrossRef25
William H. Shrank, Amanda R. Patrick, M. Alan Brookhart. (2011) Healthy User and Related Biases in Observational Studies of Preventive Interventions: A Primer for Physicians. Journal of General Internal Medicine 26:5, 546-550
CrossRef26
Wilbur H. Chen, Alan S. Cross, Robert Edelman, Marcelo B. Sztein, William C. Blackwelder, Marcela F. Pasetti. (2011) Antibody and Th1-type cell-mediated immune responses in elderly and young adults immunized with the standard or a high dose influenza vaccine. Vaccine 29:16, 2865-2873
CrossRef27
Antoine Nougairède, Rémi N. Charrel, Didier Raoult. (2011) Models cannot predict future outbreaks: A/H1N1 virus, the paradigm. European Journal of Epidemiology 26:3, 183-186
CrossRef28
Juan J. Picazo, Javier de Arístegui Fernández, Jose M. Arteagoitia Axpe, Dolores Barranco Ordóñez, Aurelio Barricarte Gurrea, Xavier Bosch José, Javier Díez Domingo, Fernando González Romo, Teresa Hernández-Sampelayo Matos, Jesús Ruiz Contreras, Lluís Salleras. (2011) Evidencias científicas disponibles sobre la seguridad de las vacunas. Vacunas 12:1, 3-34
CrossRef29
Sae Yoon Kee, Hee Jin Cheong, Byung Chul Chun, Woo Joo Kim. (2011) Influenza Vaccination Coverage Rate and Factors Associated with Vaccination in People with Chronic Disease. Infection and Chemotherapy 43:5, 406
CrossRef30
Carlos Chiatti, Pamela Barbadoro, Giovanni Lamura, Lucia Pennacchietti, Francesco Di Stanislao, Marcello M D'Errico, Emilia Prospero. (2011) Influenza vaccine uptake among community-dwelling Italian elderly: results from a large cross-sectional study. BMC Public Health 11:1, 207
CrossRef31
Goh Ohji. (2011) Prevention of infectious diseases in older adults. Nippon Ronen Igakkai Zasshi. Japanese Journal of Geriatrics 48:5, 461-465
CrossRef32
Ahmed B. Hashim, Tricia McKeever, Shona J. Kelly, Jonathan S. Nguyen-Van-Tam. (2010) Evaluation of inter-pandemic influenza vaccine effectiveness during eight consecutive winter seasons in England and Wales in patients with cardiovascular risk factors. Journal of Infection and Public Health 3:4, 159-165
CrossRef33
Roger Baxter, G. Thomas Ray, Bruce H. Fireman. (2010) Effect of influenza vaccination on hospitalizations in persons aged 50 years and older. Vaccine 28:45, 7267-7272
CrossRef34
Marta Valenciano, Esther Kissling, Bruno Christian Ciancio, Alain Moren. (2010) Study designs for timely estimation of influenza vaccine effectiveness using European sentinel practitioner networks. Vaccine 28:46, 7381-7388
CrossRef35
Orli Even-Or, Sarit Samira, Eli Rochlin, Shobana Balasingam, Alex J. Mann, Rob Lambkin-Williams, Jack Spira, Itzhak Goldwaser, Ronald Ellis, Yechezkel Barenholz. (2010) Immunogenicity, protective efficacy and mechanism of novel CCS adjuvanted influenza vaccine. Vaccine 28:39, 6527-6541
CrossRef36
P. Loulergue, P.R. Burgel, F. Carrat, B. Fritzell, J.P. Guthmann, C. Locht, U.F. Power, E. Varon, D. Dusser, O. Launay. (2010) Report of the 2nd “French Clinical Vaccinology Meeting Jean-Gerard Guillet”: Immunization and respiratory diseases. Vaccine 28:40, 6551-6555
CrossRef37
Arnold S. Monto. (2010) Seasonal influenza vaccinations: specialized products for different target groups. Vaccine 28, D14-D23
CrossRef38
Rodrigo Jiménez-García, Valentín Hernández-Barrera, Ana Lopez de Andres, Isabel Jimenez-Trujillo, Jesus Esteban-Hernández, Pilar Carrasco-Garrido. (2010) Gender influence in influenza vaccine uptake in Spain: Time trends analysis (1995–2006). Vaccine 28:38, 6169-6175
CrossRef39
Frederick J Lee, Constance H Katelaris. (2010) Senescence of adaptive immunity: key points for the general physician. Aging Health 6:4, 451-462
CrossRef40
Monique P. Curran, Isabel Leroux-Roels. (2010) Inactivated Split-Virion Seasonal Influenza Vaccine (Fluarix®). Drugs 70:12, 1519-1543
CrossRef41
Andres D. Ruiz, Christopher R. Frei, Jamie C. Barner, John J. Carson, Christine U. Oramasionwu, Jessica L. Ruiz, Kelly R. Daniels, John F. Mohr, Michael E. Klepser. (2010) Influenza vaccination rates among pharmacists. Journal of the American Pharmacists Association 50:4, 517-522
CrossRef42
Shauna T. Linn, Jack M. Guralnik, Kushang V. Patel. (2010) Disparities in Influenza Vaccine Coverage in the United States, 2008. Journal of the American Geriatrics Society 58:7, 1333-1340
CrossRef43
David RP Guay. (2010) Influenza viral infection in the elderly. Aging Health 6:3, 319-344
CrossRef44
Thomas A. Farley, Mehul A. Dalal, Farzad Mostashari, Thomas R. Frieden. (2010) Deaths Preventable in the U.S. by Improvements in Use of Clinical Preventive Services. American Journal of Preventive Medicine 38:6, 600-609
CrossRef45
F. Andersohn. (2010) Adherence to statin therapy: the key to survival?. International Journal of Clinical Practice 64:7, 843-847
CrossRef46
Jorg J. Goronzy, Lan Shao, Cornelia M. Weyand. (2010) Immune Aging and Rheumatoid Arthritis. Rheumatic Disease Clinics of North America 36:2, 297-310
CrossRef47
Peter K. Lindenauer, Michael B. Rothberg, Brian H. Nathanson, Penelope S. Pekow, Jay S. Steingrub. (2010) Activated protein C and hospital mortality in septic shock: A propensity-matched analysis*. Critical Care Medicine 38:4, 1101-1107
CrossRef48
Rosa Prato, Silvio Tafuri, Francesca Fortunato, Domenico Martinelli. (2010) Vaccination in healthcare workers: an Italian perspective. Expert Review of Vaccines 9:3, 277-283
CrossRef49
Stefania Maggi. (2010) Vaccination and healthy aging. Expert Review of Vaccines 9:3s, 3-6
CrossRef50
Tom Jefferson, Carlo Di Pietrantonj, Lubna A Al-Ansary, Eliana Ferroni, Sarah Thorning, Roger E Thomas, Tom Jefferson. 2010. Vaccines for preventing influenza in the elderly. .
CrossRef51
G. D. Deans, H. G. Stiver, J. E. McElhaney. (2010) Influenza vaccines provide diminished protection but are cost-saving in older adults. Journal of Internal Medicine 267:2, 220-227
CrossRef52
R. H H Groenwold, D. B Nelson, K. L Nichol, A. W Hoes, E. Hak. (2010) Sensitivity analyses to estimate the potential impact of unmeasured confounding in causal research. International Journal of Epidemiology 39:1, 107-117
CrossRef53
M. Buehlmann, A.F. Widmer. (2010) Isolationsmaßnahmen bei Infektionen der Luftwege. Der Internist 51:2, 161-168
CrossRef54
Rolf H.H. Groenwold, Eelko Hak, Olaf H. Klungel, Arno W. Hoes. (2010) Instrumental Variables in Influenza Vaccination Studies: Mission Impossible?!. Value in Health 13:1, 132-137
CrossRef55
Anna S. Dean, Cameron R.M. Moffatt, Alexander Rosewell, Dominic E. Dwyer, Richard I. Lindley, Robert Booy, C. Raina MacIntyre. (2010) Incompletely matched influenza vaccine still provides protection in frail elderly. Vaccine 28:3, 864-867
CrossRef56
&NA;. (2010) Seasonal Trivalent Influenza Vaccine for 2009–2010. Obstetrics & Gynecology 115:1, 174-176
CrossRef57
Tom Jefferson, Chris Del Mar, Liz Dooley, Eliana Ferroni, Lubna A Al-Ansary, Ghada A Bawazeer, Mieke L van Driel, Sreekumaran Nair, Ruth Foxlee, Alessandro Rivetti. 2010. .
CrossRef58
Sally L. Hodder, Debra Chew, Shobha Swaminathan. 2010. Adult Immunization in Women and Men. , 563-582.
CrossRef59
Sharon K. Greene, Ping Shi, M. Maya Dutta-Linn, Jo Ann Shoup, Virginia L. Hinrichsen, Paula Ray, James D. Nordin, Leslie Kuckler, Eric S. Weintraub, W. Katherine Yih. (2009) Accuracy of Data on Influenza Vaccination Status at Four Vaccine Safety Datalink Sites. American Journal of Preventive Medicine 37:6, 552-555
CrossRef60
Claude Sportès, Ronald E. Gress, Crystal L. Mackall. (2009) Perspective on Potential Clinical Applications of Recombinant Human Interleukin-7. Annals of the New York Academy of Sciences 1182:1, 28-38
CrossRef61
Pierre J.T. De Villiers, A. Duncan Steele, Louis A. Hiemstra, Ruth Rappaport, Andrew J. Dunning, William C. Gruber, Bruce D. Forrest. (2009) Efficacy and safety of a live attenuated influenza vaccine in adults 60 years of age and older. Vaccine 28:1, 228-234
CrossRef62
Lindsay J. Ledwich, Thomas M. Harrington, William T. Ayoub, Jennifer A. Sartorius, Eric D. Newman. (2009) Improved influenza and pneumococcal vaccination in rheumatology patients taking immunosuppressants using an electronic health record best practice alert. Arthritis & Rheumatism 61:11, 1505-1510
CrossRef63
Guangxi Li, Murat Yilmaz, Marija Kojicic, Evans Fernández-Pérez, Raed Wahab, W. Charles Huskins, Bekele Afessa, Jonathon D. Truwit, Ognjen Gajic. (2009) Outcome of critically ill patients with influenza virus infection. Journal of Clinical Virology 46:3, 275-278
CrossRef64
G. Li, M. Yu, C. M. Weyand, J. J. Goronzy. (2009) Epigenetic regulation of killer immunoglobulin-like receptor expression in T cells. Blood 114:16, 3422-3430
CrossRef65
P. R. Blank, M. Schwenkglenks, T. D. Szucs. (2009) Disparities in influenza vaccination coverage rates by target group in five European countries: Trends over seven consecutive seasons. Infection 37:5, 390-400
CrossRef66
Kristin L. Nichol. (2009) Challenges in evaluating influenza vaccine effectiveness and the mortality benefits controversy. Vaccine 27:45, 6305-6311
CrossRef67
Lone Simonsen, Cecile Viboud, Robert J. Taylor, Mark A. Miller, Lisa Jackson. (2009) Influenza vaccination and mortality benefits: New insights, new opportunities. Vaccine 27:45, 6300-6304
CrossRef68
B. Fireman, J. Lee, N. Lewis, O. Bembom, M. van der Laan, R. Baxter. (2009) Influenza Vaccination and Mortality: Differentiating Vaccine Effects From Bias. American Journal of Epidemiology 170:5, 650-656
CrossRef69
Gil Y. Melmed. (2009) Vaccination strategies for patients with inflammatory bowel disease on immunomodulators and biologics. Inflammatory Bowel Diseases 15:9, 1410-1416
CrossRef70
Thierry Boge, Michel Rémigy, Sarah Vaudaine, Jérôme Tanguy, Raphaëlle Bourdet-Sicard, Sylvie van der Werf. (2009) A probiotic fermented dairy drink improves antibody response to influenza vaccination in the elderly in two randomised controlled trials. Vaccine 27:41, 5677-5684
CrossRef71
Steven M. Shaw, Simon G. Williams, Nizar Yonan, James E. Fildes. (2009) Decreased Immune Responses to Influenza Vaccination in Patients With Heart Failure. Journal of Cardiac Failure 15:6, 549
CrossRef72
Bevanne Bean-Mayberry, Elizabeth M. Yano, Maria K. Mor, Nichole K. Bayliss, Xiangyan Xu, Michael J. Fine. (2009) Does Sex Influence Immunization Status for Influenza and Pneumonia in Older Veterans?. Journal of the American Geriatrics Society 57:8, 1427-1432
CrossRef73
A. van VUUREN, P. RHEEDER, E. HAK. (2009) Effectiveness of influenza vaccination in the elderly in South Africa. Epidemiology and Infection 137:07, 994
CrossRef74
Wilbur H. Chen, Bernard F. Kozlovsky, Rita B. Effros, Beatrix Grubeck-Loebenstein, Robert Edelman, Marcelo B. Sztein. (2009) Vaccination in the elderly: an immunological perspective. Trends in Immunology 30:7, 351-359
CrossRef75
Erika Wissinger, John Goulding, Tracy Hussell. (2009) Immune homeostasis in the respiratory tract and its impact on heterologous infection. Seminars in Immunology 21:3, 147-155
CrossRef76
Ya-Chi Ho, Jiun-Ling Wang, Jann-Tay Wang, Un-In Wu, Chiu-Wen Chang, Ho-Sheng Wu, Chang-Hsun Chen, Yu-Min Chuang, Shan-Chwen Chang. (2009) Prognostic factors for fatal adult influenza pneumonia. Journal of Infection 58:6, 439-445
CrossRef77
Patricia R. Blank, Matthias Schwenkglenks, Thomas D. Szucs. (2009) Vaccination coverage rates in eleven European countries during two consecutive influenza seasons. Journal of Infection 58:6, 446-458
CrossRef78
Rolf H.H. Groenwold, Eelko Hak, Arno W. Hoes. (2009) Pooling of Confounders Did Not Induce Residual Confounding in Influenza Vaccination Studies. Annals of Epidemiology 19:6, 432-436
CrossRef79
B. R. Ruf, T. Szucs. (2009) Reducing the Burden of Influenza-Associated Complications with Antiviral Therapy. Infection
CrossRef80
Herman J.M. Cools, Jacobijn Gussekloo, Joyce E.M. Remmerswaal, Ed J. Remarque, Aloys C.M. Kroes. (2009) Benefits of increasing the dose of influenza vaccine in residents of long-term care facilities: A randomized placebo-controlled trial. Journal of Medical Virology 81:5, 908-914
CrossRef81
Sum Lam, Tomasz Z. Jodlowski. (2009) <b>Vaccines for Older Adults</b>. The Consultant Pharmacist 24:5, 380-391
CrossRef82
Janet E McElhaney. (2009) Prevention of infectious diseases in older adults through immunization: the challenge of the senescent immune response. Expert Review of Vaccines 8:5, 593-606
CrossRef83
Jean-Pierre Michel, Christian Chidiac, Beatrix Grubeck-Loebenstein, Robert W. Johnson, Paul Henri Lambert, Stefania Maggi, Robert Moulias, Karl Nicholson, Hans Werner. (2009) Advocating Vaccination of Adults Aged 60 Years and Older in Western Europe:. Rejuvenation Research 12:2, 127-136
CrossRef84
Michael Schotsaert, Marina De Filette, Walter Fiers, Xavier Saelens. (2009) Universal M2 ectodomain-based influenza A vaccines: preclinical and clinical developments. Expert Review of Vaccines 8:4, 499-508
CrossRef85
Patricia R Blank, Thomas D Szucs. (2009) Increasing influenza vaccination coverage in recommended population groups in Europe. Expert Review of Vaccines 8:4, 425-433
CrossRef86
Arnold S Monto, Suzanne E Ohmit. (2009) Seasonal influenza vaccines: evolutions and future trends. Expert Review of Vaccines 8:4, 383-389
CrossRef87
F. DIJKSTRA, G. A. DONKER, B. WILBRINK, A. B. VAN GAGELDONK-LAFEBER, M. A. B. VAN DER SANDE. (2009) Long time trends in influenza-like illness and associated determinants in The Netherlands. Epidemiology and Infection 137:04, 473
CrossRef88
Danuta M. Skowronski, Gaston De Serres, Jim Dickinson, Martin Petric, Annie Mak, Kevin Fonseca, Trijntje L. Kwindt, Tracy Chan, Nathalie Bastien, Hugues Charest, Yan Li. (2009) Component‐Specific Effectiveness of Trivalent Influenza Vaccine as Monitored through a Sentinel Surveillance Network in Canada, 2006–2007. The Journal of Infectious Diseases 199:2, 168-179
CrossRef89
Nicholas T. Vozoris, M. Diane Lougheed. (2009) Influenza vaccination among Canadians with chronic respiratory disease. Respiratory Medicine 103:1, 50-58
CrossRef90
R.H.H. Groenwold, E. Hak, A.W. Hoes. (2009) Quantitative assessment of unobserved confounding is mandatory in nonrandomized intervention studies. Journal of Clinical Epidemiology 62:1, 22-28
CrossRef91
Pierre Van Damme, Froukje Oosterhuis-Kafeja, Marie Van der Wielen, Yotam Almagor, Ofer Sharon, Yotam Levin. (2009) Safety and efficacy of a novel microneedle device for dose sparing intradermal influenza vaccination in healthy adults. Vaccine 27:3, 454-459
CrossRef92
Juan Francisco Sánchez Muñoz-Torrero, Lucía Martín, Nazaret Pacheco, Maribel Martín, Pilar Guijarro, Paloma Barquilla. (2009) Ingresos hospitalarios y vacunación antigripal en pacientes de alto riesgo. Medicina Clínica 132:1, 12-15
CrossRef93
Mary Dawn T. Co, Laura Orphin, John Cruz, Pamela Pazoles, Karin M. Green, James Potts, Anita M. Leporati, Jenny Aurielle B. Babon, James E. Evans, Francis A. Ennis, Masanori Terajima. (2009) In vitro evidence that commercial influenza vaccines are not similar in their ability to activate human T cell responses. Vaccine 27:2, 319-327
CrossRef94
Nizar Ajjan. 2009. Vaccination des personnes âgées. , 107-116.
CrossRef95
Rodrigo Jiménez-García, Valentín Hernández-Barrera, Pilar Carrasco-Garrido, Ana López de Andrés, Napoleón Pérez, Ángel Gil de Miguel. (2008) Influenza vaccination coverages among children, adults, health care workers and immigrants in Spain: Related factors and trends, 2003–2006. Journal of Infection 57:6, 472-480
CrossRef96
Janet E McElhaney. (2008) Influenza vaccination in the elderly: seeking new correlates of protection and improved vaccines. Aging Health 4:6, 603-613
CrossRef97
Bram Palache. (2008) New vaccine approaches for seasonal and pandemic influenza. Vaccine 26:49, 6232-6236
CrossRef98
Rolf H.H. Groenwold, Anna M.M. Van Deursen, Arno W. Hoes, Eelko Hak. (2008) Poor Quality of Reporting Confounding Bias in Observational Intervention Studies: A Systematic Review. Annals of Epidemiology 18:10, 746-751
CrossRef99
Charles-Edouard Luyt, Alain Combes, Ania Nieszkowska, Jean-Louis Trouillet, Jean Chastre. (2008) Viral infections in the ICU. Current Opinion in Critical Care 14:5, 605-608
CrossRef100
Angelique G.S.C. Jansen, Elisabeth A.M. Sanders, Kristin L. Nichol, Anton M. van Loon, Arno W. Hoes, Eelko Hak. (2008) Decline in influenza-associated mortality among Dutch elderly following the introduction of a nationwide vaccination program. Vaccine 26:44, 5567-5574
CrossRef101
Kristin L. Nichol. (2008) Efficacy and effectiveness of influenza vaccination. Vaccine 26, D17-D22
CrossRef102
Janet E. McElhaney, Jan P. Dutz. (2008) Better Influenza Vaccines for Older People: What Will It Take?. The Journal of Infectious Diseases 198:5, 632-634
CrossRef103
Robert B. Couch. (2008) Seasonal inactivated influenza virus vaccines. Vaccine 26, D5-D9
CrossRef104
Michael L Jackson, Jennifer C Nelson, Noel S Weiss, Kathleen M Neuzil, William Barlow, Lisa A Jackson. (2008) Influenza vaccination and risk of community-acquired pneumonia in immunocompetent elderly people: a population-based, nested case-control study. The Lancet 372:9636, 398-405
CrossRef105
Edward A Belongia, David K Shay. (2008) Influenza vaccine for community-acquired pneumonia. The Lancet 372:9636, 352-354
CrossRef106
Rodrigo Jiménez-García, Valentín Hernández-Barrera, Pilar Carrasco-Garrido, Ana Lopez de Andres, Maria Mercedes Esteban y Peña, Ángel Gil de Miguel. (2008) Coverage and predictors of influenza vaccination among adults living in a large metropolitan area in Spain: A comparison between the immigrant and indigenous populations. Vaccine 26:33, 4218-4223
CrossRef107
Dena L. Schanzer, Joanne M. Langley, Theresa W.S. Tam. (2008) Co-morbidities associated with influenza-attributed mortality, 1994–2000, Canada. Vaccine 26:36, 4697-4703
CrossRef108
Jonathan A McCullers, B Keith English. (2008) Improving therapeutic strategies for secondary bacterial pneumonia following influenza. Future Microbiology 3:4, 397-404
CrossRef109
Hana M El Sahly, Wendy A Keitel. (2008) Clinical data on Fluarix ® : an inactivated split seasonal influenza vaccine. Expert Review of Vaccines 7:6, 713-719
CrossRef110
Tymen Keller, Viola B Weeda, Carlo J van Dongen, Marcel Levi, Tymen Keller. 2008. Influenza vaccines for preventing coronary heart disease. .
CrossRef111
Q. Sue Huang, Liza D. Lopez, Lisa McCallum, Bruce Adlam. (2008) Influenza surveillance and immunisation in New Zealand, 1997-2006. Influenza and Other Respiratory Viruses 2:4, 139-145
CrossRef112
Odile Launay, Sophie Grabar, Frédéric Bloch, Corinne Desaint, David Jegou, Christophe Lallemand, Robert Erickson, Pierre Lebon, Michael G. Tovey. (2008) Effect of sublingual administration of interferon-α on the immune response to influenza vaccination in institutionalized elderly individuals. Vaccine 26:32, 4073-4079
CrossRef113
Daniel R. Martin, Mark E. Brauner, Joseph F. Plouffe. (2008) Influenza and Pneumococcal Vaccinations in the Emergency Department. Emergency Medicine Clinics of North America 26:2, 549-570
CrossRef114
Jeffrey M. Caterino. (2008) Evaluation and Management of Geriatric Infections in the Emergency Department. Emergency Medicine Clinics of North America 26:2, 319-343
CrossRef115
Anne Schuchat, Beth P Bell. (2008) Monitoring the impact of vaccines postlicensure: new challenges, new opportunities. Expert Review of Vaccines 7:4, 437-456
CrossRef116
Pengjun Lu, Carolyn B. Bridges, Gary L. Euler, James A. Singleton. (2008) Influenza vaccination of recommended adult populations, U.S., 1989–2005. Vaccine 26:14, 1786-1793
CrossRef117
Alex J Elliot, Douglas M Fleming. (2008) Influenza and respiratory syncytial virus in the elderly. Expert Review of Vaccines 7:2, 249-258
CrossRef118
R. Groenwold, A. Hoes, K. Nichol, E Hak. (2008) Quantifying the potential role of unmeasured confounders: the example of influenza vaccination. International Journal of Epidemiology 37:6, 1422-1429
CrossRef119
Janet E McElhaney. (2008) Influenza vaccination in the elderly as a strategy to improve vaccine effectiveness. Aging Health 4:1, 33-35
CrossRef120
Robert J Taylor, Lone Simonsen. (2008) Breaking through to daylight: new opportunities for influenza control. Future Virology 3:1, 7-11
CrossRef121
(2007) Effectiveness of Influenza Vaccination. New England Journal of Medicine 357:26, 2728-2731
Full Text122
Treanor, John D., . (2007) Influenza — The Goal of Control. New England Journal of Medicine 357:14, 1439-1441
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