Summary of the NACI literature review on the comparative effectiveness of subunit and split virus inactivated influenza vaccines in older adults
Bibliographic record
Abstract
BACKGROUND: Subunit and split virus inactivated influenza vaccines (IIV) are two commonly used types of seasonal influenza vaccines in Canada. The comparative effectiveness of these two formulations is particularly relevant for older adults, as older adults have reduced influenza vaccine effectiveness and experience more severe influenza than younger adults. OBJECTIVE: To compare the vaccine effectiveness and immunogenicity of unadjuvanted, standard-dose subunit IIVs versus unadjuvanted, standard-dose split virus IIVs in adults 65 years of age and older. METHODS: written protocol based on rapid review methods was developed that included studies published in 2007 or later in the EMBASE, MEDLINE and ClinicalTrials.gov databases with terms used in the objective. Due to the small number of records returned, hand searches of reference lists were completed, the publication date limit was removed, three additional databases (the Cochrane Central Register of Controlled Trials, Scopus and Web of Science) were searched, and studies including adults 60 years of age and older were included. Data from included studies were extracted into evidence tables and quality assessments were completed. The results were synthesized narratively. RESULTS: Eight eligible studies were identified. In the three studies that assessed vaccine effectiveness of subunit and split virus IIVs, there were no statistically significant differences in vaccine effectiveness in adults 65 years of age and older against laboratory-confirmed infection with any influenza virus strain, or against laboratory-confirmed infection with influenza A(H1N1), A(H3N2) or B virus, specifically. In the five studies that assessed immunogenicity, the findings were not consistent and the overall quality of immunogenicity evidence was weak. CONCLUSION: The National Advisory Committee on Immunization (NACI) concludes that there is insufficient evidence to determine significant differences in the vaccine effectiveness or immunogenicity of unadjuvanted, standard-dose subunit and split virus IIVs in adults 65 years of age and older (Grade I evidence).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.011 | 0.051 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.010 | 0.008 |
| Bibliometrics | 0.019 | 0.015 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.003 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.014 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".