This is how stuff happens....
http://news.bbc.co.uk/2/hi/health/3719990.stm
http://news.bbc.co.uk/2/hi/health/3719990.stm
Scientists have shown that tiny changes to modern flu viruses could render them as deadly as the 1918 strain which killed millions.
A US team added two genes from a sample of the 1918 virus to a modern strain known to have no effect on mice.
Animals exposed to this composite were dying within days of symptoms similar to those found in human victims of the 1918 pandemic.
The research is published in the journal Nature.