The influenza pandemic of 1918/1919 was a unique event in recorded history, costing on the order of 50 million lives within the time span of only several months. Reverse genetics techniques made it possible to reconstruct the extinct pandemic virus using the nucleotide sequence obtained from RNA fragments present in lung samples of victims of the 1918 influenze virus. This allowed for the testing of current vaccines on the virus and led to a better understanding of the molecular basis of virulence and the mechanisms by which pandemic influenza viruses are transmitted. From the Series:Global Infectious Disease