latter. It is not as good as completely preventing infection which is what an antibody might do, but because that is so difficult, and some might say it is almost impossible to get an antibody to neutralise all the variety of HIV viruses that there are out there, this is an alternative way to go to try and make sure the immune responses people make are better and they are less likely to develop disease. Q: How far are we from a vaccine that prevents HIV infection? AM: We are a little way closer than we used to be, but we are still a long way off I think. There was a recent trial two years ago in Thailand which took about 5 years to do. It showed that there was a 30% reduction in infection in people who are vaccinated. For a flu vaccine for example we would hope for 100% protection, so 30% is not terribly good but is a lot better than nothing.  And if that result can be repeated, and that is a big if , but if it is repeated then I think we have opened the door slightly. I think that it will be possible to improve on that 30% and get it up to 50%, 60%, 70% and then we really would have a vaccine. But that whole process would probably take at least 5 years to get to that more efficient vaccine, and then another 5 years to roll out to give