AIDS vaccine remains elusive

Radio ScopeCase Notes, BBC4, Tuesdays, 9 p.m. Would you take part in a trial for the HIV/AIDS vaccine? Given the sketchy knowledge that most of us have about vaccines, it has to be one of the hardest sells in medical trials.

But as one of the contributors to Case Notes, BBC Radio 4's medical programme, said about her involvement in such a new trial, "we have to help find a vaccine for the disease, it's too important not to take part", and a doctor followed up by explaining what the woman involved already knew - it is not possible to become infected from the vaccine.

Finding a vaccine for HIV/AIDS has become one of the biggest challenges in medical science. The programme played a clip from a speech given by the then US Health Secretary, Margaret Heckler, that from a distance of 20 years later, seems hopelessly naïve.

Cases of AIDS were first noted in 1981 and the virus that caused it discovered three years later.

In the speech, Heckler triumphantly announced the discovery of the virus, said that there was now a simple and inexpensive blood test to detect it and promised that in two years' time there would a vaccine! It hasn't happened and depressingly the best estimate for an AIDS vaccine is sometime in the next six to 10 years.

There are 11 key vaccines for diseases ranging from the flu to German measles but the reasons why an AIDS vaccine is proving so illusive were outlined by Prof Jonathon Weber of the Imperial College, London.

The virus's complexity is one reason - there are so many variants. A more fundamental problem, Weber explained, is that "there is no immune response to model a vaccine on".

With AIDS, Weber said, people are either infected or they are not and there is no natural immunity. He is involved with a new trial for an AIDS vaccine that, as was noted in the programme, effectively means going back to the drawing board.

Up until now the search for a vaccine has concentrated on developing an antibody-based vaccine whereby a vaccine was made from the outer coating of the HIV virus.

The antibodies did stimulate the immune system of the volunteers taking part in the trials and they did go on to develop some antibodies to the virus, but not enough to render them immune from the disease.

Weber has now turned away from this antibody approach in favour of a cellular approach, the basic idea of which is to attempt to make the body generate a "T cell" that will kill viral infected cells.

Presenter Dr Mark Porter noted, "it's a depressing time for HIV vaccines", and given the resources and brain power that has gone into finding such a vaccine over the past two decades, and with no successful results, Porter's comments are understated to say the least.

The WHO's statement 24 years ago that smallpox was now extinct was celebrated the world over. The same announcement for HIV/AIDS seems, on the evidence presented in the programme, very far away indeed.