Scientific research, common in many countries and led to the swine flu H1N1 Influenza A virus emerged in the change of seasons showing not spread like regular flu viruses.

Made in the USA on the subject of genetic analysis and laboratory experiments, the normal virus pass-through the (easily spread) providing the structure with respect to the H1N1 virus in the genetic structure deficiencies which, therefore, the pass-through of the normal flu virus so that was revealed.
Dutch researchers, the studies about the H1N1 virus in the nose of the virus can remain for a long time that there is a suitable environment, where the residence time increases, more and lead to poor results and an increased likelihood of spread has determined that.