After the tube bombings in 2005, we all became suspicious of packages and bags on the tube. For a while. After the first wave of swine flu earlier this year we all eyed with hostility anyone coughing or sneezing. This is wearing off. The atmosphere on the tube seems to be closer to those innocent days of yesteryear. We naturally want to be able to trust our fellow passengers and, though the threats remain, that level of trust always finds a way of rising back up.
It is of course hard to know just what the real threats may be. All risks are a matter of probability, but most people don't understand the nature of probability (which is why so many play the National Lottery). Based on experience, the likelihood of being caught in a terrorist attack is amazingly low, way lower than the chances of being in a car crash or a street fight. But whilst we are still warned about unattended packages, nobody warns us to be careful on the road when leaving the Tube.
As for flu, some people are getting it all the time and swine flu is not the only nasty strain we might encounter. I don't know if I should worry about it or not. The nurse at my local GP tells me they are not particularly bothered about it. I don't know anyone who has had it, or who knows someone who has it. Even if you get it, it is not clear what the probability of it turning into a life-threatening condition may be. So on the whole, best to ignore it for the moment. What with a vital decider coming up in the Ashes series, we have more important things to strain the old adrenaline glands.