An expression of concern

The publishers, editor and authors have noted that the following commissioned Review Article: Ilaria Capua, Dennis J. Alexander, Avian influenza infections in birds – a moving target, Influenza and Other Respiratory Viruses 2007; 1: 11–18 published online in November 2006 did not credit that some of the content of this article had previously appeared in the following Review Article: Dennis J. Alexander, An overview of the epidemiology of avian influenza, Vaccine 2007; 25: 5637–5644 and was not referenced as such. The publisher and editor apologize for not identifying this apparent overlap at the time of publication.