But what nobody knew at the time was that in reality it was a close call. A study commissioned by the WHO showed that approximately 24% of the entire population of the world, including half of all schoolchildren, were infected with Influenza A(H1N1) during the first year of the pandemic in 2009, according to data from 19 countries. It is also thought the virus killed 200,000 people around the world.
|[From: Morens et al: The Persistent Legacy of the 1918 Influenza Virus]|
Maybe, just maybe, the Influenza A(H1N1) virus from 2009 just needs one single mutation become as lethal as his grandfather was back in 1918.
 Van Kerkhove et al: Estimating age-specific cumulative incidence for the 2009 influenza pandemic: a meta-analysis of A(H1N1)pdm09 serological studies from 19 countries in Influenza and Other Respiratory Viruses - 2013
 Garten RJ, Davis CT, Russell CA, et al. Antigenic and genetic characteristics of swine-origin 2009 A(H1N1) influenza viruses circulating in humans in Science - 2009