>>>Every 20 seconds, a child dies from a disease that could have been prevented with a safe and effective vaccine, according to the U.S. Centers for Disease Control and Prevention.

Measles is one of the leading causes of childhood deaths worldwide. Not only does measles kill, but it can leave children blind, deaf or developmentally disabled, even while they are still in their mothers' wombs. Yet the disease can be prevented with just two doses of a safe and inexpensive vaccine.

When measles broke out in the U.S. state of North Carolina earlier this year, Pamela McCall was one of the health officials who tracked down the cases.

"It is one of those immunizations required for school entry, so most people, most children, are vaccinated and most people are vaccinated against it," said McCall.

That's why fewer than a dozen people in North Carolina actually got the disease.  In the U.S., vaccines have made many diseases rare, or non-existent. Dr. Chesley Richards is with the Centers for Disease Control and Prevention.

“Vaccines have made an enormous impact on improving health in the United States. Diseases like smallpox, measles, polio, they’ve been eliminated or eradicated in the United States and in the case of smallpox, it’s been eradicated worldwide," said Richards.

But there's much more to be done.  A long-sought vaccine against malaria could save some of the more than 660,000 people, mostly children, killed each year by the mosquito-borne parasite.

The Centers for Disease Control says vaccines give children a chance to grow up healthy, go to school, and improve their lives.

Dr. Anthony Fauci, with the National Institutes of Health, agrees.

"If you had to pick out one intervention, if you balance the investment that you make in the research and the implementation and the health benefits, vaccines have to be at either the top of the list or very much on the short list," said Fauci.

Since the Measles and Rubella Initiative was launched twelve years ago, worldwide measles deaths have been reduced by nearly 75 percent, according to the CDC.

Besides preventing many childhood diseases, vaccines also protect against hepatitis, influenza, and even cervical  cancer.  Soon, they may free the world from the scourge of polio.

Dr. Fauci says vaccines cut health-care costs because preventing a disease is cheaper than treating one.

The World Health Organization is urging countries around the world to invest more in immunization programs so more children can grow up healthy and strong.