Initial epidemiological findings in the European Union following the declaration of pandemic alert level 5 due to influenza A (H1N1)

The recent detection of a novel influenza A(H1N1) virus has led to the first WHO declaration of a Public Health Event of International Concern under the International Health Regulations (IHR 2005). Here we review the early epidemiological findings of confirmed cases in Mexico, the United States, Canada and EU/EFTA countries. Strengthened surveillance and continued, transparent communication across public health agencies globally will be necessary in coming months.