5. Control Arm in Trials

Consensus:

Use of a substance that is not active against HIV in the control arm of a preventive HIV vaccine trial is scientifically and ethically acceptable in the absence of proven effective preventive HIV vaccines.

Controversy:

Some participants were concerned about the lack of benefit that results from being randomized to placebo. It was suggested that another vaccine such as hepatitis B or tetanus vaccine could be given to participants in the control arm, for the sake of increasing benefit. The choice of vaccine would need to be appropriate for the population (i.e. a vaccine should not be given against a disease for which there already exists significant immunity in the population.) However, some participants were of the opinion that those in the control arm should not be treated any differently from those in the treatment arm of the trial. This argument rested on the principle that both arms deserve equal benefit (the treatment arm is not receiving a proven benefit), and that scientific interpretation of the results may be clouded by providing vaccination against a disease other than HIV.

It was suggested that the scientific community might rely too readily on the power of randomized placebo-control trials, and that there needs to be encouragement to consider other study designs that could provide adequate data without the risks inherent in randomization.

In some cultures, participants feel cheated if they are aware they may be receiving a placebo.