Here is a great article about how science works. This ties in with our One Book, One College theme on infectious disease an public health.
Basically, scientists noticed that children in Europe who were given a specific H1Ni vaccine in 2009 had trouble sleeping (about 1 in 16,000 children). The drug maker decided to fund research to try to understand why. There was already a theory that narcolepsy was caused by out-of-control immune cells. The research findings suggest that this theory is correct. However, there are also other children who did not receive the vaccine who suffered narcolepsy. The possibility could be that that vaccine stimulated the rogue immune cells or perhaps it was just the flue virus. The findings move us one step closer to understanding.
You can read this article on the Atlantic Website here: Swine Flu Connection Provides Clues About Narcolepsy.
Now, anti-vaccine folks would point to this as a problem with vaccines. This is a side effect. They do not often note the number of lives saved from stopping this outbreak. They also do not recognize that this is a great example of the creation of knowledge and the way that science solves problems. We are understanding the mechanics of infectious disease in great detail and depth.