Efficacy and Effectiveness of High-Dose Influenza Vaccine for Older Adults: A Systematic Review and Meta-Analysis
Bibliographic record
Abstract
Seasonal influenza epidemics are responsible for significant disease burden each year, especially in adults over the age of 65. Only recently have there been vaccines that are formulated specifically for individuals 65 years of age or older, one of which, Fluzone®High-Dose (IIV3-HD), has received widespread use in the US. This study aims to review the evidence of efficacy and effectiveness of IIV3-HD compared with standard dose influenza vaccine (IIV3) in individuals aged 65 years or older against clinical outcomes plausibly related to influenza. A systematic review of four electronic databases and other sources was conducted for randomized and observational studies assessing vaccine efficacy or effectiveness (VE) of IIV3-HD against clinical outcomes such as influenza-like illness, hospital admissions and death in adults 65 years of age or older. A meta-analysis was conducted by separately extracting individual VEs reported in the studies and estimating random-effects pooled efficacy against each of the clinical outcomes. 7 eligible studies (4 randomized trials and 3 observational studies) were identified following the screening of 1,816 studies. All of these studies reported relative VE (rVE) of IIV3-HD vs. IIV3, and not absolute efficacy/effectiveness of IIV3-HD. Of those, 5 studies reported rVE for IIV3-HD vs. IIV3 against influenza-like illness, 6 studies reported rVE against hospital admissions, and 3 studies reported rVE against death. IIV3-HD demonstrated improved protection against influenza-like illness (rVE=18.3%, 95% CI: 7.0 to 28.3%), and was also more effective at preventing hospital admissions due to influenza illness (rVE=19.4%, 95% CI: 6.7 to 30.4%), pneumonia (rVE=22.4%, 95% CI: 5.0 to 36.5%), cardiorespiratory events (rVE=12.0%, 95% CI: 4.9 to 18.6%), and death following a hospital admission for influenza (rVE=22.2%, 95% CI: -18.2 to 48.8%). IIV3 also had a modest but not statistically significant impact on all-cause hospital admissions (rVE= 7.3%, 95% CI: -1.5 to 15.4%) and all-cause death (rVE=0.8%, 95% CI: -4.2 to 5.5%). There is significant evidence demonstrating IIV3-HD is more effective than standard dose influenza vaccine at reducing the clinical outcomes typically associated with influenza infection in older adults. This study was funded by sanofi pasteur. J. Lee, sanofi pasteur: Employee, Salary; G. Lam, sanofi pasteur: Employee, Salary; T. Shin, sanofi pasteur: Employee, Salary; J. Kim, sanofi pasteur: Co-op Student, Educational support; A. Krishnan, sanofi pasteur: Co-op Student, Educational support; B. Seet, sanofi pasteur: Employee and Shareholder, Salary; D. Neame, sanofi pasteur: Employee and Shareholder, Salary; D. P. Greenberg, sanofi pasteur: Employee and Shareholder, Salary; A. Chit, sanofi pasteur: Employee, Salary
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.019 | 0.003 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".