Spanish Flu's Fatal Timing

The Spanish Flu was likely so lethal because young adults might have had a mismatched immunity to the influenza virus.

The Spanish flu epidemic of 1918 killed between 50 and 100 million people worldwide, and was one of history's most lethal plagues. It also killed a huge number of young, healthy people in the prime of life, which is quite unusual for the flu, which normally most affects the old and young. Canadian scientist Dr. Michael Worobey, a Professor of Ecology and Evolutionary Biology at the University of Arizona in Tucson, thinks the reason for the flu's unusual behaviour might be due to a different flu outbreak, nearly 30 years before - in 1889. That flu primed the immune system of the children it infected at the time to one kind of flu virus. But the Spanish flu was from a different family of viruses, and so people in that age group had the wrong kind of immunity when disaster struck.

Related Links

• Paper in PNAS
• New York Times article
• National Geographic article
• Dr. Worobey previously on Quirks about the history of HIV