I know people are dying in Mexico, and a few elsewhere no doubt, but I really don't see what the big deal is... well, not for us in the UK anyway - if people get symptoms, they phone nhs direct, and then the nhs send you some tamiflu or whatever.. and you'll probably be fine.
Why so many people are dying in Mexico - I've no idea, but from what I've seen on the news, people have been quite blase about it.
What does worry me a little, is that the WHO has the impression that the UK is quite well equipped to deal with it - the first thing I would've expected was that people would be screened / tested upon returning from Mexico, as did people on flights from Mexico, who were told that they were going to be screened upon return to London... but they weren't.
