In a discovery that might allow scientist to stay ahead of the bird flu they've found that the key to flu mutation lies in two amino acids. They studied the differences between the 1918 flu that spread quickly and killed 50 million and another version that killed but wasn't easy to spread. It seems that a small change in the amino acids was enough to turn the hard to spread flu into it's far more deadly cousin.
This is the type of breakthrough that might let scientist understand and stop the spread of bird flu and other deadly varieties. It's amazing that such a small change can have such a massive effect!