There are at least nine HIV-1 genetic

Vaccine update While much more basic research is still needed, a successful vaccine against HIV is believed to be scientifically feasible (see Box page 59). However, this optimism is tempered by continued under-investment in HIV vaccine development. It is estimated that approximately US$ 600 million a year is invested in HIV vaccine R&D, the majority from the US National Institutes of Health. But not enough is being spent to develop candidate vaccines based on HIV subtypes circulating in developing countries, or to strengthen vaccine evaluation sites in these countries where 95% of infections and most deaths occur.

There are at least nine HIV-1 genetic subtypes circulating in the world. Most research to date has focused on a vaccine for HIV subtype (or clade) B, which is the main subtype in the Americas, Australia, Japan and western Europe. The subtypes mainly found in sub-Saharan Africa and Asia – where the epidemic has hit hardest – are A, C, D and E and there is no assurance that a vaccine based on subtype B will be effective against these others. In addition, vaccine efficacy may vary in different populations because of genetic make-up.

The first Phase I trial of an HIV candidate vaccine was carried out in the United States in 1987. Since then, more than 30 different candidate vaccines, developed by different companies and using different technologies, have been tested in 80 Phase I and II trials – mainly in the United States and Europe, although more recently also in developing countries (Brazil, China, Cuba, Haiti, Kenya, Peru, Thailand, Trinidad and Uganda).