On a beautiful morning in my hometown of Walnut Creek, California, I sat watching my daughter playing in the park. There she was, along with many other kids, swinging, sliding, and running with the kind of pure joy you see only in children.
Behind us lay a green soccer field, filled with two teams of kids competing for nothing but bragging rights and team spirit. Their parents along the sidelines were enjoying the action. My daughter is just 2 years old, but I looked forward to the day I would be one of those parents, cheering her on to victory.
If it were 60 years ago, many children on this playground and soccer field might have been crippled or died from childhood diseases for which we now have vaccines. Children growing up in that era were at risk for