A flow

evolved from the Spanish flu

U.S. study officials said June 29 that all able to infect humans are influenza A virus caused the beginning of the last century, "Spanish flu" pandemic of H1N1 influenza virus and future generations, but the virus in about 90 years of evolutionary process, danger of weakening.

The study was conducted by the U.S. National Institute of Allergy and Infectious Diseases Anthony Fauci, who completed research published June 29 in the "New England Journal of Medicine" online.

forge that occurred in 1918-19 the Spanish flu is a symbol of humanity in the history of public health incidents and trigger the outbreak of H1N1 influenza virus has been evolving, all can infect a human Flow virus directly or indirectly from its variability. But the past several decades, a stream virus has reduced the harm caused. One reason is that drug research and development and public health level, on the other hand, have reduced the dangers of influenza virus.

researchers said that the human influenza virus and the immune system about 90 years seemed to go through a complex "dance" with each other are changing in response to changes in each other.