Gardasil is a vaccine, and vaccines are regulated somewhere else in FDA. But let me answer the question about drugs, because I think your comments about gardasil are relevant to many drugs as well.
First of all, when a drug comes to market, we know there are still certain things we will be learning about the drug safety profile. As I mentioned in my opening remarks, it's really impossible to know everything about a drug once it comes on the market. We approve drugs because we believe the potential benefits exceed the potential risks, and our monitoring of drugs throughout their life cycle is aimed at ensuring that the potential benefits exceed the risks. We do much more monitoring in the post-approval period to monitor potential risks than we do to monitor potential benefits or new benefits.
That balance is often difficult to determine, the balance between the benefit and the risk, and in some cases we bring this to public advisory committees. Our new program in the last eight or ten years to have risk management programs is really designed to ensure that certain drugs whose benefits exceed the risks in certain narrowly defined conditions adhere to those conditions so the benefits do exceed the risks. But learning about the safety of drugs once they're on the market is a complex process. One of the complexities is to determine if the adverse reactions we're seeing are actually due to the drug or if they're due to patients' underlying diseases or to other factors. So it's never a particularly easy question.