Parents take numerous precautions to keep their children safe: caps over electrical outlets, latches on cabinets, car seats, bicycle helmets and swimming lessons.

Another part of raising healthy children is having them vaccinated to ward off dangerous diseases. Thanks to vaccines routinely administered in childhood, smallpox has been eradicated from the globe and polio nearly has been eliminated. Incidences of measles, mumps, whooping cough and tetanus have declined significantly.

Numbers from the Centers for Disease Control and Prevention tell the successful story. Before polio vaccines were developed, 13,000 to 20,000 cases were reported each year in this country, leaving children in braces, crutches, wheelchairs and iron lungs. In 2006, just 2,000 cases were reported in the world.

Hib meningitis used to kill 600 children each year and leave many survivors with deafness, seizures or mental retardation. Since the vaccine was introduced in 1987, incidence of the disease has dropped by 98 percent.

Virtually every American used to get measles. Now there's been a 99 percent reduction, but without immunizations the rate will surge. That's why health officials are worried by the CDC's recent review, which shows measles cases at their highest level since 1997. The numbers are small, 131 cases, but 63 were children whose parents rejected vaccination.

The measles virus is not simply a matter of getting small red spots on the skin. Twenty percent of the people who get measles wind up in the hospital, many with serious complications. In the late '50s and early '60s, before a vaccine was available, 450 measles-related deaths occurred annually.

No vaccine is 100 percent safe and, as infection rates have fallen, some parents have been lulled into the false belief that vaccines no longer are necessary, or that getting inoculations poses greater risks than forgoing them.

This is not so. One child in a million will develop a severe allergic reaction or encephalitis from the measles, mumps, rubella vaccine. But of children who get the measles, six in 100 will develop pneumonia, one in 1,000 will get encephalitis and two in 1,000 will die.

Keeping our children safe includes keeping them safe from preventable diseases.