When it comes to providing aid, developing innovations and making bold steps that change the course of history, the United States is usually on the front lines.

Investments in immunization yield a rate of return on a par with educating our children - and higher than nearly any other development intervention.

For just a few dollars a dose, vaccines save lives and help reduce poverty. Unlike medical treatment, they provide a lifetime of protection from deadly and debilitating disease. They are safe and effective. They cut healthcare and treatment costs, reduce the number of hospital visits and ensure healthier children, families and communities.

The return on investment in global health is tremendous, and the biggest bang for the buck comes from vaccines. Vaccines are among the most successful and cost-effective health investments in history.

As variable as flu is, HIV makes flu look like the Rock of Gibraltar. The virus that causes AIDS is the trickiest pathogen scientists have ever confronted.

As many times as [HIV] changes its clothes, it's still wearing the same socks, and now our job is to make sure we get the body to really hate those socks.

Leadership is about vision and responsibility, not power.