Since it came out Friday, you may have missed it.

Researchers looking into the 1918 flu have done mouse studies to look at what made that flu so deadly.

The first comprehensive analysis of an animal’s immune response to the 1918 influenza virus provides new insights into the killer flu, report federally supported scientists in an article appearing online today in the journal Nature. Key among these insights, they found that the 1918 virus triggers a hyperactive immune response that may contribute to the lethality of the virus. Furthermore, their results suggest that it is the combination of all eight of the 1918 flu virus genes interacting synergistically that accounts for the exceptional virulence of this virus.

It seems like people tend to ignore the flu as something that’s under control. But in the United States 20,000 to 30,000+ people die every year from the flu. An understanding of what made the flu of 1918 so deadly may help as we try to prepare for the next flu pandemic.