A series of simple shots given from infancy to the teen years is fending off some serious illnesses in millions of kids. In fact, a new study shows that routine childhood immunizations in the United States have spurred the largest-ever decline in cases of many devastating — but now highly preventable — diseases.

The Centers for Disease Control and Prevention (CDC) looked at historical records dating as far back as 1900 to compare how often people today are catching, being hospitalized, or dying from 13 potentially deadly diseases that are now being fought off by vaccines.

The researchers report:

• a 100% (or near total) drop in the number of cases and deaths from diphtheria, measles, smallpox, rubella (German measles), paralytic poliomyelitis (the most severe type of polio), and invasive Haemophilus influenzae type b (Hib) disease (once the leading cause of meningitis in kids)
• huge declines in cases of mumps (down 96%) and tetanus (down 93%)

Why Immunize?

You may wonder why your child needs to be vaccinated if these diseases are no longer prevalent in the United States. But the fact is, infectious diseases that are rare or nonexistent in the United States because of immunization programs — like measles and polio — are still huge problems in other parts of the world.

So, if immunization rates fell, a disease introduced by an unimmunized person (either someone coming into the United States or an American traveling overseas) could cause serious damage in an unprotected population.

Granted, a single child's chance of catching a disease is low if everyone else is immunized. But each child who isn't immunized gives these highly contagious diseases one more chance to spread. Just consider these scenarios:

• A measles epidemic broke out in the United States between 1989 and 1991, when lapsing rates of immunization among preschoolers led to a sharp increase in the number of measles cases, deaths, and children with permanent brain damage.
• Whooping cough (pertussis) struck Japan and the United Kingdom in the 1970s after immunization rates declined. And the disease, which can be fatal in young babies, has made a comeback in the United States, too. By 2004, the number of whooping cough cases spiked past 25,000 — the highest level since the 1950s. The most common carriers of the disease are adults, who catch pertussis as their own childhood immunizations wear off and can then unknowingly pass it on to young infants who haven't been immunized yet.
• Polio, which had completely vanished from the United States, cropped up in a tiny Amish community in central Minnesota in late 2005.

It's only safe to stop vaccinations for a particular disease when that disease has been totally wiped out worldwide, as in the case of smallpox.

What This Means to You

It's important to make sure kids get all of the immunizations they need at every age — not just in the infant and toddler years, when most vaccines are given. In fact, routine vaccines and boosters are also recommended between the ages of 4 and 6, 11 and 12, and then again before teens enter college.

And new boosters and vaccines are added to the childhood immunization schedule all the time — like the now-recommended chickenpox booster for 4- to 6-year-olds, and the human papillomavirus (HPV) vaccine for 11- to 12-year-old girls.

Even parents need to stay up to date with all of their shots. Why? Because some childhood vaccines — like those for whooping cough and tetanus — don't provide lifelong immunity, which means they lose their effectiveness over time. So, not only could you catch some potentially serious diseases, but you could pass them on to your kids, too.

It's wise to call your doctor to find out if you or anyone else in your family needs to get updated on vaccines, especially if you're planning to travel to any area of the world where certain diseases still exist. And, especially if you have kids 5 years old and under, make sure everyone in your household gets the flu vaccine, which is effective even when received as late as January.

Reviewed by: Steven Dowshen, MD
Date reviewed: December 2007

Source: "Historical Comparisons of Morbidity and Mortality for Vaccine-Preventable Diseases in the United States," Journal of the American Medical Association (JAMA), Nov. 14, 2007.