Preliminary findings for a new vaccine against the AIDS virus have delivered mixed results. The vaccine provided little or no protection for whites and Hispanics, but appeared to reduce the rate of infection in blacks and Asians.
The large scale Phase III trial involved 5,400 people all considered to be at high risk of acquiring the AIDS virus, HIV. The California-based company running the US Food and Drug Administration approved three-year trial, VaxGen, released initial results yesterday.
The firm acknowledged the vaccine did not show "a statistically significant reduction of HIV infection within the study population as a whole". It did show a significant reduction in infection amongst certain vaccinated groups.
The reduction of infection amongst the entire sample of volunteers taking part was 3.8 per cent, an advantage that would have been negated by the study's margin of error. Unexpectedly however, the 314 black participants experienced a 78 per cent reduction in the rate of infection.
The infection rate was reduced by 67 per cent for all non-white volunteers including Asians but excluding Hispanics.
The FDA-approved trial was considered ethically difficult. A third of all participants received a dummy placebo vaccine, there was criticism the trial could engender a false sense of security that might encourage risky behaviour.
The company had to counsel volunteers to practice safe sex, warning them that the vaccine might not work and also that one in three vaccines given in this randomised, double-blind trial were an ineffective placebo.
AIDS has overwhelmed health care systems in many countries, particularly Africa where a majority of the 20 million AIDS deaths and 40 million cases of HIV infection have occurred.
There are a number of vaccine trials underway including one in Uganda that only recently got underway using a vaccine developed at Oxford University.
The VaxGen trial is the only study to have progressed to large scale testing. Its full results are expected for release late next month.
The vaccine stimulates the body's immune system, causing it to produce antibodies against HIV.