Observational studyThe Journal of infectious diseases2017
The Importance of Frailty in the Assessment of Influenza Vaccine Effectiveness Against Influenza-Related Hospitalization in Elderly People.
Observational study in The Journal of infectious diseases, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT01517191 (Sentinel Surveillance for Influenza Requiring Hospital Admission Canadian Adults), which is not on this map. Cited by 106 papers, 3 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Sentinel Surveillance for Influenza Requiring Hospital Admission Canadian Adults
Who cites it
106 citing papers in PubMed, 3 syntheses or guidelines pooled it, 171 citations in OpenAlex.
- Influenza vaccine effectiveness according to frailty status in adults aged ≥ 50 years: a systematic review and meta-analysis.BMC infectious diseases · 2026Pooled it
- Immunogenicity of influenza vaccine in elderly people: a systematic review and meta-analysis of randomized controlled trials, and its association with real-world effectiveness.Human vaccines & immunotherapeutics · 2020Pooled it
- The Use of Test-negative Controls to Monitor Vaccine Effectiveness: A Systematic Review of Methodology.Epidemiology (Cambridge, Mass.) · 2020Pooled it
- Relative Effectiveness of High-Dose Versus Standard-Dose Influenza Vaccination Against Hospitalizations and Deaths According to Frailty Score: A Post Hoc Analysis of the DANFLU-1 Randomized Trial.The Journal of infectious diseases · 2026Trial
- Oseltamivir Reduces 30-Day Mortality in Older Adults With Influenza: A Pooled Analysis From the 2012-2019 Serious Outcomes Surveillance Network of the Canadian Immunization Research Network.Open forum infectious diseases · 2025Trial
- Immunogenicity of BNT162b2 as a first booster after a ChAdOx1 primary series in a Thai geriatric population living with frailty.The journal of nutrition, health & aging · 2024Trial
- An Easy-to-Implement Clinical-Trial Frailty Index Based on Accumulation of Deficits: Validation in Zoster Vaccine Clinical Trials.Clinical interventions in aging · 2022Trial
- Induction of Cross-Reactive Hemagglutination Inhibiting Antibody and Polyfunctional CD4+ T-Cell Responses by a Recombinant Matrix-M-Adjuvanted Hemagglutinin Nanoparticle Influenza Vaccine.Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 2021Trial
- Recombinant Zoster Vaccine Is Efficacious and Safe in Frail Individuals.Journal of the American Geriatrics Society · 2021Trial
- Medical conditions at enrollment do not impact efficacy and safety of the adjuvanted recombinant zoster vaccine: a pooled post-hoc analysis of two parallel randomized trials.Human vaccines & immunotherapeutics · 2019Trial
- Evaluation of two frailty indices, with practical application in a vaccine clinical trial.Human vaccines & immunotherapeutics · 2019Trial
- Influenza Vaccine-Induced Antibody Responses Are Not Impaired by Frailty in the Community-Dwelling Elderly With Natural Influenza Exposure.Frontiers in immunology · 2018Trial
- What Drives Influenza Vaccination in People with Diabetes? Evidence from the National Health Surveys of 2020 and 2023 in Spain.Epidemiologia (Basel, Switzerland) · 2026Article
- Observational
- Human Metapneumovirus Epidemiology Among Middle-aged and Older Adults Hospitalized With Acute Respiratory Infection.The Journal of infectious diseases · 2025Observational
- Relationship Between Frailty and Respiratory Syncytial Virus Infection in Hospitalized Older Adults.Open forum infectious diseases · 2025Article
- Uptake of Influenza Vaccine among Older Adults with Cardiovascular Comorbidities.Arquivos brasileiros de cardiologia · 2025Article
- COVID-19 vaccine safety and effectiveness at 3 months in institutionalized old people.BMC geriatrics · 2024Article
- Assessing the Impact of Frailty on Infection Risk in Older Adults: Prospective Observational Cohort Study.JMIR public health and surveillance · 2024Observational
- Predicting major clinical events among Canadian adults with laboratory-confirmed influenza infection using the influenza severity scale.Scientific reports · 2024Article
46 more citing papers are in PubMed but not listed here.
Corrections and comments
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Authors and funding
32 authors at 18 institutions in 2 countries.
Funding
Abstract
Background: Influenza is an important cause of morbidity and mortality among older adults. Even so, effectiveness of influenza vaccine for older adults has been reported to be lower than for younger adults, and the impact of frailty on vaccine effectiveness (VE) and outcomes is uncertain. We aimed to study VE against influenza hospitalization in older adults, focusing on the impact of frailty. Methods: We report VE of trivalent influenza vaccine (TIV) in people ≥65 years of age hospitalized during the 2011-2012 influenza season using a multicenter, prospective, test-negative case-control design. A validated frailty index (FI) was used to measure frailty. Results: Three hundred twenty cases and 564 controls (mean age, 80.6 and 78.7 years, respectively) were enrolled. Cases had higher baseline frailty than controls (P = .006). In the fully adjusted model, VE against influenza hospitalization was 58.0% (95% confidence interval [CI], 34.2%-73.2%). The contribution of frailty was important; adjusting for frailty alone yielded a VE estimate of 58.7% (95% CI, 36.2%-73.2%). VE was 77.6% among nonfrail older adults and declined as frailty increased. Conclusions: Despite commonly held views that VE is poor in older adults, we found that TIV provided good protection against influenza hospitalization in older adults who were not frail, though VE diminished as frailty increased. Clinical Trials Registration: NCT01517191.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.