The authors acknowledge several methodological limitations in this study, and the data refer to a small sample of children.

Despite a reduction in pertussis among younger children and infants, rates of pertussis-related sickness and death remain high compared with rates for other vaccine-preventable diseases in England and Wales.

​This study, strong of an almost complete follow-up of all children born in Denmark from 2003 to 2008, provides evidence that the DTaP-IPV-HiB vaccine is not associated to an overall increased risk of febrile seizures and epilepsy.

The authors assess the risk of pertussis in children in California relative to the time since the fifth dose of DTaP from 2006 to 2011 (this period included a large outbreak in 2010).

​This letter to the editor raises the issue of the adaptation of B. pertussis to vaccine selection pressure as one of the reasons for the increase number of cases of whooping cough reported in several countries.

Starting 15 September 2011, ECDC will be coordinating the former EUVAC.NET network. It is a surveillance network covering measles, mumps, rubella, congenital rubella, pertussis and varicella EU Member States and three countries of the European Economic Area. Data will be hosted by the European Surveillance System (TESSy) at ECDC.