SPEAK OUT

HIV
VACCINE TRIALS BEGIN IN FEBRUARY

This overview of world AIDS vaccine trials was written for SpeakOut! at our request by the World Health Organisation

A note from SpeakOut!: an AIDS vaccine would only be for HIV negative people, the world does not expect to have a vaccine - if any - before the year 2007 or 2010. It will not help people already infected.

WHO:
The global investment in HIV vaccines is very low. Not more than US$ 300 million in 1999 (compared with US$ 3 billion used to purchase antiretroviral drugs in Europe and the US the same year). From those US$ 300 million, some US$ 200 are provided by the US National Institutes of Health of the USA to fund a wide range of research: from basic science to clinical trials. More resources would help, but lack of resources is not our only problem. There are scientific obstacles to solve (we especially need more information on the type of immune responses that a vaccine should induce to protect against HIV infection or disease).

Most of the effort is being directed to develop vaccines against strains of the virus circulating in the industrialised world (subtype B strains). Very little is being done to develop vaccines against strains in Africa (mostly subtypes C, A and D). A note of caution: we do not know the significance of those subtypes in terms of vaccine induced protection.

HIV vaccine trials have been going on since 1987, and more than 6000 healthy volunteers have participated in different Phase I/II trails, mostly in the US, but also in some developing countries (Brazil, China, Cuba, Thailand and Uganda). Those Phase I/II trials have shown that the vaccines are safe and that they induce immune responses specific for the HIV.

But phase I/II trials can not tell us if the vaccines are actually effective in protecting against HIV infection or disease. For that we need to conduct large scale Phase III efficacy trials. The first Phase III trials started in 1998 in the US and in 1999 in Thailand. At the end of next year we will have the initial results from those trials. These vaccines have been developed based on
gp120 from strains B and E, which are prevalent in these countries (but not in Africa).

Although we do not know if those vaccines (based on gp120) will be effective in the US or Thailand, one thing we think we know: If they are effective in the US and/or Thailand, they will not be effective against the subtypes present in Africa. Some US$ 10-15 million would be required now to start producing equivalent experimental vaccines appropriate for Africa. But, please remember,
we still do not know if gp120 vaccines will work.

At the end of September, 2000 a group of African scientists decided to initiate an African AIDS Vaccine Programme, to promote and co-ordinate HIV vaccine research in Africa, in close collaboration with the international community. Its Steering Committee is preparing a plan of action (with budget) that will be ready early next year.

WHO-UNAIDS will serve as the Secretariat.

The only HIV vaccine trial in Africa (a phase I/II with 40 volunteers) was conducted in Uganda from 1999 to 2000. It used a canarypox-HIV vaccine based on clade B. That vaccine approach is aimed at inducing cell-mediated immunity, which is known to be most cross-reactive that the antibodies induced by envelope vaccines (gp120).

The next vaccine planned to be tested in Africa is a DNA plus Vaccinia Ankara-HIV recombinant developed in Oxford (and being tested in Oxford) to be initiated in Kenya late in 2000 or early 2001. This vaccine is based on clade A virus, which is the most prevalent in that country.

The South Africa AIDS Vaccine Initiative (SAAVI) is supporting several projects,including the development of clade C candidate vaccines.