The Spanish influenza virus pandemic of 1918 killed more than 20 million people worldwide. In September 7
They analysed sequences of the hemagglutinin (HA) gene from 30 H1-subtype influenza isolates, using the sister-scanning method and a maximum likelihood method. They suggest that recombination replaced a central region of the human-lineage HA gene with sequences from the swine-lineage virus.
In the same issue of