@ free spirit
...who is saying that festivals are 'high risk'?
& are they seen as any higher risk than schools, hospitals, underground trains, airports, theatres, Wimbledon crowds or places of work?
well, one of the aspects of work I cover for festivals is working as a freelance festival safety officer, so it's a part of my job to be able to assess all types of risk associated with festivals, and if I get that wrong, and something goes badly wrong, then it'd be me not the licensee that ended up in court for it... so, I'm saying that festivals are high risk activities, make of that what you will.
I also covered the spread of diseases as a small part of my degree (a degree that some use to go on to become environmental health officers, though it was more environment than health based), and can remember enough of that to know that large gatherings of people are classed as being high risk factors in the spread of diseases such as the flu, particularly when they involve people travelling from lots of different places to the event, and they involved people being in close proximity to a lot of different people... ie festivals.
also, yes I'd place festivals higher than any of your other examples with the possible exception of wimbledon, though I think festivals would still rank higher than any of them. The reason being that people travel from so many different places to festivals, and spend so much time in close proximity to so many other different people from so many different places, that it's very likely that anyone going to a festival with swine flu would pass it on to many many more people (10s, possibly hundreds) from many different previously unaffected parts of the country.
worth noting that glastonbury actually had a plan in place to mitigate the risk associated with swine flu, which as far as I can work out, seems to have been based around immediate isolation and containment of anyone onsite reporting with symptoms that could potentially be swine flu, followed by a medivac offsite. This is fine for a festival like glastonbury that has full onsite medical facilites to rival many cottage hospitals, with a huge army of volunteer doctors, nurses etc. It's not very practical for most smaller festivals who simply don't have the medical resources onsite to enable this to happen, or would need to pay significant additional extra money for the increased medical resources to mitigate the risk to the satisfaction of the local environmental health inspector / NHS etc.
Bottom line though, is that if significant numbers of people end up being diagnosed with swine flu, with the source being traced back to Glastonbury, then it'd be virtually impossible for any other festival to even attempt to win the arguement that they could mitigate the risk sufficiently by measures other than shutting the festival completely, as glastonbury has the best medical resources and infrastructure of any festival in the UK. Hence my opening statement.