Evidence suggests that many young people in 1918 and quite a few in this outbreak are killed by a "cytokine storm" -- the body's own immune reaction, which floods the lungs with fluid. Young adults generally have strong immune systems.In some ways, the strong immune systems of young people becomes our greatest enemy. Our immune systems work in such a delicate balance with our bodies... so it becomes too easy for some virulent invaders turn that to their own advantage.
This is the first time that I've heard the phrase "cytokine storm" used. A query in PubMed reveals that it has been used lightly in the past. Only 50 or so articles have used the phrase "cytokine storm", with the original published use taking place in 1993. Google Trends doesn't have much data to show for it, just a spike in search queries taking place in early 2006... but I anticipate that this will change quickly. In the process of political spin doctoring, all it takes to change peoples' perceptions is the coinage of a new term and turn it into something to be feared and reviled.
"Cytokine storm" sounds much more scarier than "bird flu." The human flu for most people is something that doesn't even warrant the effort to get a vaccine each year. The word "cytokine" is a mysterious thing in our bodies which will be translated as a "immune system messenger" that can easily send the wrong signals to our bodies.
Here's a cytokine that comes to my mind. Tumor Necrosis Factor alpha (TNF alpha) moderates our inflammatory response. TNF can kill cancer cells, hence the name. It can also kill healthy cells. TNF is involved in death when people go into shock. People who have high concentrations of TNF over time start wasting away and get cachexia.
See how spooky these things become? And thats always in our bodies, ready to be unleashed. When the H5N1 strain mutates from an "avian flu" to a "human flu that can kill millions," language like this will cultivate a more appropriate sense of fear in the public... as long as they don't get carried away in the hysteria. After all, gross hysteria and overreaction is just what this virus needs to kill you...