H1N1

H1N1

About H1N1

Influenza A (H1N1) virus is the subtype of influenza A virus that was the most common cause of human influenza (flu) in 2009. Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a small fraction of all seasonal influenza. H1N1 strains caused a small percentage of all human flu infections in 2004–2005.[1] Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza).

Contributions by WAS 4.250, Green Squares, and TimVickers.