Flu vaccine is far and away the most underutilized.

For most mothers, vaccinations become a matter of faith - faith in pharmaceutical companies, faith in public health officials - and I think there's been an erosion of faith.

Vaccines are not traditionally big money makers. They're given once or a few times in one's life, so they're never going to be blockbusters.

I've never seen this level of anger at parents who've chosen not to vaccinate their children.

People are reticent to give a newborn the hepatitis B vaccine and often delay it.

Physicians who care for adults generally don't think about vaccines as much as pediatricians do, and adults think of vaccines as a kid thing.

When you're in the womb, you're in a sterile environment. When you enter the birth canal and the world, you're not. Very quickly, you have, living on the surface of your body, trillions of bacteria, literally trillion.