Influenza Vaccine Effectiveness in Preventing Admissions With Influenza During the 2014-2015 Influenza Season: A Test-Negative Hospital-Based Study, in the Valencia Hospital Network for the Study of Influenza and Respiratory Viruses Disease, Valencia (Spain)
Bibliographic record
Abstract
Background. The 2014/15 influenza season was characterised by the circulation of A(H3N2) viruses belonging to clade 3C.2a and 3C.3a, distinct from the A/Texas/50/2012(H3N2)-like (clade 3C.1) reference for the 2014/15 vaccine. In addition, B Yamagata lineage and few A(H1N1)pdm09 were identified. Preliminary influenza vaccine effectiveness (IVE) estimates in Europe and North America reported null to low IVE against confirmed influenza acute respiratory infection. Methods. We performed a test-negative study in ten hospitals that provided care to 2,351,526 inhabitants. We enrolled consecutive consenting admissions of non-institutionalized, 18 years old or older subjects, with onset of influenza-like-illness (ILI) within 7 days of hospitalization. We obtained combined nasopharyngeal swabs and influenza was confirmed by RT-PCR. A split trivalent vaccine (Vaxigrip; Sanofi Pasteur MSD) was offered free of charge to subjects targeted for influenza vaccination. We considered a subject as immunized when vaccinated 15 or more days before ILI onset. We estimated IVE as (1-odds ratio)*100, taking into account clustering by hospital and epidemiological week. Results. We enrolled 2713 admissions, 653 influenza positive (546 (84%), A(H3N2); 56 (9%) B Yamagata; 38 (6%) A no subtyped; 9 (1%) A(H1N1)pdm09 and 4 (0.6%) B with no lineage) and 2060 influenza negative; 87 (19.5%) < 65 years old were influenza positive compared to 566 (25.0%) ≥ 65 years old; 1334 (65%) influenza negative were vaccinated compared to 383 (59%) influenza positive; 158 (35%) < 65 years old were vaccinated compared to 1559 (69%) ≥ 65 years old. For subjects over 18 years of age, overall adjusted IVE was 18% (−1 to 34%) and 50% (13% to 71%) in preventing A(H3N2) or influenza B admissions, respectively. When considering subjects 65 years old or older, adjusted IVE was 32% (15% to 46%); 30% (12% to 45%) and 60% (27% to 78%) in preventing admissions with influenza, influenza A(H3N2) or influenza B, respectively. Conclusion. The vaccine conferred moderate protection against the risk of admission with influenza. Low effectiveness against A(H3N2) was most possibly due to mismatch, whereas, vaccination more than halved admissions with influenza B. Disclosures. J. Puig-Barberà, Sanofi Pasteur Institution: funding for the study, Research support; A. Mira-Iglesias, Sanofi Pasteur Institution: funding for the study, Research support; M. Tortajada-Girbés, Sanofi Pasteur Institution: funding for the study, Research support; F. X. López-Labrador, Sanofi Pasteur Institution: funding for the study, Research support; Belenguer-Varea, Sanofi Pasteur Institution: funding for the study, Research support; M. Carballido-Fernández, Sanofi Pasteur Institution: funding for the study, Research support; E. Carbonell-Franco, Sanofi Pasteur Institution: funding for the study, Research support; C. Carratalà-Munuera, Sanofi Pasteur Institution: funding for the study, Research support; R. Limón-Ramírez, Sanofi Pasteur Institution: funding for the study, Research support; J. Mollar-Maseres, Sanofi Pasteur Institution: funding for the study, Research support; M. D. C. Otero-Reigada, Sanofi Pasteur Institution: funding for the study, Research support; G. Schwarz-Chavarri, Sanofi Pasteur Institution: funding for the study, Research support; J. Tuells-Hernández, Sanofi Pasteur Institution: funding for the study, Research support; V. Gil-Guillén, Sanofi Pasteur Institution: funding for the study, Research support
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".