Influenza A(H5N1): an overview of the current situation.

Influenza viruses continue to threaten the world with a new pandemic. While currently attention is focused on the newly emerged A(H1N1) virus, the avian influenza A(H5N1) virus is still a cause of concern. Extended research is focused on the genetic evolution of the viruses, as well as their susceptibility to available antiviral drugs. One of the major priorities of the World Health Organization is to develop candidate vaccines, four of which are already licensed for use in the European Union. Since the last influenza pandemic in 1968, our knowledge of the influenza virus and its biology has greatly increased, revealing new avenues in the research for antiviral strategies and the development of effective vaccines.