Lots, but there are some very scary similarities.
Okay, I’m not really qualified to write about flu epidemics, but the increased incidence of swine flu reports , made me return to an article that I read a little while ago.
You might recall back in Jan/Feb this year, the latest Facebook craze was the 25 Things About Me meme . Chris Wilson in Slate Magazine  suggested that this particular craze, and many other cultural movements followed the same exponential growth of a biological epidemic. The model in the article showed how the meme started out slowly, but once it had enough carriers, exploded. Indeed, the internet has allowed cultural movements and knowledge to spread much faster than ever before. Similarly, international travel has meant that biological viruses move much quicker than they did back in 1918 .
The difference between the 25 Things virus, and a flu epidemic is that when Myers considered the 25 things model, she suggested that a person was “contagious” for one day – the day that they created their own 25 Things list. A flu epidemic has a significantly longer period of being contagious.
Not sure what that means for swine flu, but it gives you a sense of how the Susan Boyle , Mirandasings  and “chk, chk, boom ” memes work their way around the intertubes . And you won’t be surprised to hear that marketers are spending a fair bit time with epidemiologists trying to understand how this knowledge might transfer to viral marketing (beyond the relatively simplistic stuff  floating around at the moment).
But beware, viral marketers. There is more to a virus than simply putting it out there. Most viruses (just like cultural movements) tend to evolve, mutate or simply die. Most epidemiologists struggle to pinpoint why some viruses live, grow and prosper, while others simply don’t get past the first transfer.
The notes section of Facebook was there back in 2006, and the 25 Things meme went through a large number of variations (16 things, 5 things, 100 things) before it took off – it seems that 25 things was enough, and worth the effort, than say 16 things or 100 things about me. So, like all things human, it is not as simple as creating a virus (or viral marketing campaign), spreading it around, and watching it grow. No-one really knows the variables that makes a virus spread (although they do know how to track the spread after a certain point).
So don’t believe the hype – viral marketing is just as hard, “hit and miss”, and expensive, as other forms of marketing. And anyone who tells you that they have the formula should be avoided like the plague!