We're creating this alliance, GAVI, that has helped buy the vaccines that were in the rich world but not getting to the poor kids, getting a very cheap price and figuring out the cold chain, getting the delivery right, and then funding research for new vaccines. A lot of them are coming along. We've got a meningitis vaccine out, got that through large parts of Africa. That has been a huge success.

I have this very positive view of the world getting better and better. The list of things that could be huge setbacks is not very long: A nuclear war, climate change and epidemics.

I understand how every healthy child, every new road, puts a country on a better path, but instability and war will arise from time to time, and I'm not an expert on how you get out of those things.

If I hadn't given my money away, I'd have had more than anyone else on the planet.

Does the universe exist only for me? It's possible. If so, it's sure going well for me, I must admit.

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.

I remember in 1980 or 1981 looking at a list of people who had made a lot of money in the computer industry and thinking, Wow, that's amazing. But I never thought I'd be on that list. It's clear I was wrong. I'm on the list, at least temporarily.