Mr. Kennedy: Exactly what evidence would persuade you to recommend measles vaccines for all eligible American children? Would anything convince you?

For 2 decades, and at great cost to your personal reputation, you have fought to magnify the voices of parents who are skeptical of vaccine safety. This sacrifice has gained you the trust of many parents concerned about vaccine side effects. They will listen to you.

In contrast, the large majority of infectious disease researchers tell us that the benefits of vaccination far outweigh the costs. They warn that the current drop in child vaccination rates is setting the stage for a catastrophic measles outbreak, putting countless children—even those of the parents you work so hard to support—at extreme risk. Who is right, and how can we know?

Are you a reasonable man, willing to change your position when confronted with the appropriate evidence? Surely you are, and so, can you tell us right now, before we hand over power to you, what “appropriate evidence” would look like to you? With the power and resources of the U.S. Health Department, you will be able to request any experiment or data collection service you need to reach a conclusion.

Again, Mr. Kennedy: Exactly what evidence would persuade you to recommend measles vaccines for all eligible American children?

Jon Perry