Impacts on influenza A(H1N1)pdm09 infection from seasonal influenza vaccine and related regional factors : systematic review and meta-analyses
Bibliographic record
Abstract
BACKGROUND \nInfluenza is an infectious disease that has significant public health impact due to its high prevalence and mortality. In early 2009, a novel influenza A(H1N1) virus emerged in Mexico and the USA, then rapidly spread worldwide and caused the first influenza pandemic of the 21st century. However, it is still controversial that whether seasonal influenza vaccine can provide a cross-protection against influenza A(H1N1) pdm09 infection. Since the 2009 pandemic occurred, numbers of studies focusing on this issue have been published, yet no confirmed conclusion was drawn. Therefore, further quantitative evaluation is needed to provide more reliable evidence. The objective of this study is to assess the cross-protection of seasonal influenza vaccination against 2009 pandemic A(H1N1) influenza illness, and explore the impact of seasonal influenza activities on this association. \n \nMETHODS \nI followed the PRISMA statement and searched the PubMed, MEDLINE, Ovid Embase, The Cochrane Library databases, SCOPUS and CNKI. Randomized control trials, cohort studies, case-control studies assess the effect of seasonal influenza vaccine against influenza A (H1N1)pdm09 illness published in English and Chinese from 2009 to July 2013 were identified. The quality of included studies was assessed by the Jadad scale and the Newcastle-Ottawa Scale. I used the I2statistic, and Begg's funnel plot for assessment of heterogeneity and publication bias respectively. The software Review Manager 5.2 was used for generating the pooled effect with corresponding 95% confidence intervals and forest plots. Subgroup analysis was performed based on the study locations and previous circulating influenza viruses. \n \nRESULTS \n20 studies were included in the meta-analyses. There is a non-significant 19% reduced risk of pandemic influenza illness in the countries combined data based on case-control studies(OR=0.81, 95% CI=0.60 to 1.08). While, for RCTs, a non-significant increase risk in seasonal influenza vaccinees was observed(RR=1.13, 95% CI=0.56 to 2.29). For the subgroup analysis, a significant 35% to 50% cross-protection was observed in South America and Europe, but an opposite result was observed in Canada(OR=1.44, 95% CI=0.83 to 2.50). Besides, the results indicate that there is no association between seasonal influenza vaccination and ILI. No publication bias was detected. \n \nCONCLUSIONS \nThe findings partially support the hypothesis that seasonal vaccine may offer moderate cross-protection against laboratory-confirmed pandemic influenza A(H1N1) illness in general. Further immunological research is needed to understand the mechanism behind these findings.
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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 | 0.014 | 0.039 |
| Meta-epidemiology (narrow) | 0.003 | 0.001 |
| Meta-epidemiology (broad) | 0.017 | 0.037 |
| Bibliometrics | 0.009 | 0.010 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.003 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 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".