Setting up redundant servers for static HTML files is easy, but a database replication in a complex database-backed application is another.

FORBES: What You Need to Know About NoSQL Databases

Prof Wendy Barclay, chair in influenza virology at Imperial College London, said other more complex viruses make proteins at different times during replication, but what is clever is that influenza can do this in such a simple way.

BBC: Flu virus 'knows when to attack'