The phase 1 studies will be carried out at three locations in Maharashtra, Tamil Nadu and at an unspecified site in the northeast. A 32-member advisory board has been set up to monitor the trials. The total cost of development is estimated at US $100 million.

The Boston-based biotechnology firm Therion Biologics will supply the vaccine for the trial. IAVI has entered into a vaccine development partnership with Therion to bring together researchers from India and Therion to build preventive HIV vaccines designed specifically for India.

IAVI will pay $800,000 to Therion over a three-year period for limited access to the technology. Subsequently, Therion will transfer the manufacturing technology to an Indian company with a 10-per cent royalty on cost price (development and manufacturing costs). The product is likely to be ready for trials by end 2002 or early 2003.

The strain of the virus prevalent in the Indian subcontinent is HIV-C. The proposed vaccine is a modified Vaccinia Ankara (MVA) formulation, into which pieces of cloned genetic material from HIV-C will be inserted. MVA, a harmless version of poxvirus, is the vector (transport mechanism).

Unlike the current vaccination programmes, which are aimed primarily at children, Aids vaccination efforts will initially target the high-risk populations, including truck drivers, commercial sex workers, adolescents and drug-users. One reason for selective vaccination could be the efficacy of the vaccine, which IAVI says could be in the range of 30-to-90 per cent.

Efforts for an effective vaccine model for HIV have always been mired in controversy. In India too, if the trail progresses to the late phases, it may encounter with scientific and social issues.

For instance, persons who are targeted for recruitment into large-scale phase III trials are likely to be drawn from communities that have been historically marginalised and disenfranchised where HIV is most prevalent. Targeted communities, say experts, often exhibit a strong distrust of the federal government and public health research, especially around the issue of HIV/Aids.

On the scientific front, immunisation may result in participants developing vaccine-induced HIV antibodies, and because HIV antibody testing is sometimes a requirement for accessing insurance, medical care, and employment, trial participants may be exposed to discrimination based on antibody test results, experts say.

More importantly, trial participants may become careless after vaccination and may neglect prevention altogether.