“Drug regulators are expected to analyse the CoA to ensure the placebo and the experimental drug are appropriately matched, to eliminate an unknown variable. However, the details relating to the contents of a placebo are often unknown to independent researchers and remains proprietary information of the drug manufacturers. For example, the in trials of Gardasil (HPV vaccine), the manufacturer often used a placebo containing amorphous aluminium hydroxyphosphate sulfate (AAHS) – an adjuvant to enhance immune response – and has kept the formulation a proprietary secret.”