2496. A Comparative Evaluation of the Burden of Disease Caused by Influenza A and Influenza B During the 2011–2012, 2012–2013, and 2013–2014 Influenza Seasons in Canada
Bibliographic record
Abstract
When assessing burden of influenza disease, influenza B has typically been associated with infection in children and young adults, and is considered less prevalent and/or severe in older adults. We sought to assess the burden of influenza type A disease compared with influenza type B disease in Canadian adults admitted to hospital with laboratory-confirmed influenza. The Serious Outcomes Surveillance (SOS) Network of the Canadian Immunization Research Network (CIRN) conducted active surveillance for laboratory-confirmed influenza in adults (≥16 years) hospitalized across Canada during the 2011–2014 influenza seasons. Eligible patients who were admitted to hospital with any acute respiratory illness or symptom had a nasopharyngeal swab collected and tested for influenza virus using reverse transcriptase polymerase chain reaction (PCR). Demographic/clinical information, as well as in-hospital outcomes were collected. Frailty Index scores were also recorded at baseline and 30-days after discharge, when possible, in patients ≥65 years. Patients with influenza A and B were compared using descriptive statistics; discrete outcomes were compared using Chi-squared (χ2) tests; continuous outcomes were compared using student’s t-tests. Overall, there were 3484 influenza A cases and 1375 influenza B cases enrolled in the SOS Network from 2011 to 2014. Mean age was significantly different between influenza A and influenza B cases (mean age of influenza A: 65.8, mean age of influenza B: 71.2, P < 0.01). A significantly larger proportion of influenza B patients were admitted from long-term care (A: 5.5%, B: 12.1%, P < 0.01). There was no significant difference with respect to length of hospitalization (influenza A: 11.1 days, influenza B: 10.27 days, P = 0.07) or mortality (A: 9.01%, B: 9.45%, P = 0.63) between influenza A and B. Patients with influenza B were significantly more frail prior to the onset of illness (A: 0.21, B: 0.22, P < 0.01). Current attitudes consider influenza A to be the more significant virus in terms of morbidity and mortality in adults. However, influenza B is responsible for similar duration of hospitalization and similar mortality rates. In addition, influenza B predominantly affected the frail elderly and thus optimizing influenza B protection is important in this population. M. K. Andrew, GSK: Grant Investigator, Research grant. Pfizer: Grant Investigator, Research grant. Sanofi Pasteur: Grant Investigator, Research grant. T. F. Hatchette, GSK: Grant Investigator, Research grant. Pfizer: Grant Investigator, Research grant. Abbvie: Consultant, Speaker honorarium. S. A. McNeil, GSK: Grant Investigator, Research grant. Pfizer: Grant Investigator, Research grant. Merck: Collaborator and Consultant, Contract clinical trials and Speaker honorarium. Novartis: Collaborator, Contract clinical trials. Sanofi Pasteur: Collaborator, Contract clinical trials.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.004 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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".