In 1990, one in 10 children died before the age of five. That's now down to one in 20, and vaccines were the single biggest factor in that. Had it stayed at 10 percent, 122 million more children would have died.

The computer will live your life, listen to you and understand you better than humans can.

Measles will always show you if someone isn't doing a good job on vaccinations. Kids will start dying of measles.

It is a high bar to say that it's more fun than working on software because the work at Microsoft that both Melinda [Gates] and I did was thrilling. We were making breakthroughs and empowering people.

The scientific understanding of some of these [childhood] diseases is advancing quite rapidly. There's some things like premature birth or nutrition, first day deaths that we need a lot more insights so that we can build the tools to solve those problems.

It is hard to sell Congress and the American people on foreign aid. Is it harder to do that than it is to sell billionaires on the idea that they should give all their money away.

What's amazing is, if young people understood how doing well in school makes the rest of their life so much interesting, they would be more motivated. It's so far away in time that they can't appreciate what it means for their whole life.