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. 2011;6(12):e28346.
doi: 10.1371/journal.pone.0028346. Epub 2011 Dec 2.

Publication delay of randomized trials on 2009 influenza A (H1N1) vaccination

John P A Ioannidis  1 , Lamberto Manzoli, Corrado De Vito, Maddalena D'Addario, Paolo Villari
Affiliations

Publication delay of randomized trials on 2009 influenza A (H1N1) vaccination

John P A Ioannidis et al. PLoS One. 2011.

Abstract

Background: Randomized evidence for vaccine immunogenicity and safety is urgently needed in the setting of pandemics with new emerging infectious agents. We carried out an observational survey to evaluate how many randomized controlled trials testing 2009 H1N1 vaccines were published among those registered, and what was the time lag from their start to publication and from their completion to publication.

Methods: PubMed, EMBASE and 9 clinical trial registries were searched for eligible randomized controlled trials. The units of the analysis were single randomized trials on any individual receiving influenza vaccines in any setting.

Results: 73 eligible trials were identified that had been registered in 2009-2010. By June 30, 2011 only 21 (29%) of these trials had been published, representing 38% of the randomized sample size (19905 of 52765). Trials starting later were published less rapidly (hazard ratio 0.42 per month; 95% Confidence Interval: 0.27 to 0.64; p<0.001). Similarly, trials completed later were published less rapidly (hazard ratio 0.43 per month; 95% CI: 0.27 to 0.67; p<0.001). Randomized controlled trials were completed promptly (median, 5 months from start to completion), but only a minority were subsequently published.

Conclusions: Most registered randomized trials on vaccines for the H1N1 pandemic are not published in the peer-reviewed literature.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Time from start to publication for 2009 H1N1 vaccine trials overall (A) and according to sponsor (B).
Figure 2
Figure 2. Cumulative sample size in launched and published trials of 2009 H1N1 vaccines over time.
Figure 3
Figure 3. Time from start to completion (A) and from completion to publication (B) for 2009 H1N1 vaccine trials.
Figure 4
Figure 4. Scatter plot showing the impact factor of published randomized trials by time of publication.
See this image and copyright information in PMC

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