Expression of Concern: Immune Protection Induced on Day 10 Following Administration of the 2009 A/H1N1 Pandemic Influenza Vaccine

Following the publication of the article ‘‘Immune Protection Induced on Day 10 Following Administration of the 2009 A/ H1N1 Pandemic Influenza Vaccine’’, the Editors of PLoS ONE noticed that the article described findings from a clinical trial. In line with PLoS ONE’s editorial policies for clinical trials; the article should have included a trial registration number for the study and a copy of the trial protocol. The Editors followed up on this matter with the authors, who indicated that the trial had not been registered at a public registry. The Editors were also concerned about the documentation and clarifications provided by the authors in response to the request for the study protocol and details on ethical approval for the study. In the light of the concerns raised in relation to the article, the Editors contacted the Institut Pasteur of Shanghai to request an institutional investigation into the research reported in the article. The Institut Pasteur of Shanghai has now completed their institutional investigation. While the investigation has not questioned the results reported in the article, the enquiry has revealed concerns about some aspects of the study. In the light of the findings of this enquiry, the Editors issue this expression of concern to make readers aware of the following concerns in relation to this trial: