1918 flu pandemic linked to human, bird virus gene swap

The 1918 pandemic flu, which killed up to 50 million people, may have originated after a human virus took genetic material from a bird virus. Young adults born between 1880 and 1900 were probably more susceptible to the 1918 flu virus because they had been exposed to a distinct H3N8 virus as children and didn’t have the same flu immunities as their elders, researchers report April 28 in the Proceedings of the National Academy of Sciences.

The distinct flu strains people are exposed to as children may influence which age groups experience more deaths during seasonal flu epidemics and from the H5N1 and H7N9 viruses, the scientists conclude.