Immunization programs have been one of the greatest public health success stories in history. In the words of the American Academy of Pediatrics (AAP), “Immunization continues to be the most effective method of preventing disease, disability, and death in children.” In fact, childhood diseases that can be prevented by vaccines are at their lowest levels in history in the United States.

Vaccines protect your child by introducing a small amount of a killed or weakened disease-causing germ or substance into his body. This causes your child’s immune system to build up antibodies and other defenses to fight the disease. These defenses that are developed in response to a vaccine remain with your child and enable him to fight off the disease if he is ever exposed to it. In this way, he becomes immune to the disease.

But despite the success of vaccination programs, outbreaks of serious childhood illnesses still occur: In 1989 and 1991, measles epidemics hit the United States, even though there is a vaccine to prevent the disease. As a caring and loving parent, it is your responsibility to have your child vaccinated according to the schedule your child’s doctor will give you.

Why Some Children Aren’t Immunized Even When They Should Be

Immunization works only if everyone participates. The U.S. Centers for Disease Control and Prevention still considers the immunization rate in this country to be too low. In 1998, only 79 percent of children ages 19 to 35 months had received a complete series of vaccines. This puts all children at risk. Let’s take a look at some of the reasons kids aren’t immunized even when they should be.

Mistaken Belief That the Danger Is Gone

Often parents believe it isn’t necessary to immunize their children because almost everyone else in the United States has gotten shots and so there is no one to spread the disease. We live in a global environment today, however, where we and people from other nations move freely around the world. Diseases move just as freely. As long as diseases such as polio or measles exist anywhere on the globe, your child is at risk and vaccinations are necessary. Potential epidemics are just a plane ride away. And in the case of tetanus, even vaccinating every other child on the planet won’t protect your child from getting this disease. That’s because tetanus is caused by bacteria in soil that can contaminate a wound.

Fear of Contracting Disease from the Vaccination

Another common misconception that keeps some parents from getting their children vaccinated is the belief that a vaccine will give the child the disease it is intended to prevent. The truth is, it is impossible to get the disease from a vaccine that is prepared with dead bacteria or viruses or that is made with only a part of the bacteria or virus. The only risk of contracting disease from a vaccine comes from vaccines made from live or weakened viruses, like the oral (but not the injectable) polio vaccine and the chicken pox vaccine (varicella). But even this risk is very small: For every 2.4 million oral polio vaccinations given each year, there is approximately one reported case of the disease resulting from the vaccine.

But the U.S. Centers for Disease Control and Prevention now recommends that a vaccine carrying only the killed polio virus be used entirely eliminating the risk of children contracting the disease from the vaccine. The few blisters and mild fever that may occur in some children who receive the chicken pox vaccine are much less of a threat than the more serious complications that can occasionally occur if a child gets the disease itself; these include pneumonia, meningitis, serious blood infections, and even death.

Fear of Injections

Some parents may skip scheduled vaccinations because they’re worried the injection will hurt their children. But these parents should remember that the pain and distress of disease is far worse than the brief pain of an injection.

Fear of Bad Reactions

Some parents worry that their child may have a bad reaction to the vaccination. While some children have minor reactions—including redness and swelling where the shot was given, fever, and sometimes rash—more severe problems rarely occur. As with any medicines, a child can have a serious allergic reaction to a vaccine, but this is rare. A small number of children may have a brief seizure due to a fever caused by vaccines (just as can happen in children with a high fever from any cause), but this does not cause any permanent harm to the child. Although the risk of serious side effects from common vaccines is very low, you should always call your child’s doctor if you have any questions or if your child experiences problems after receiving the vaccine. Reports linking vaccines to multiple sclerosis, sudden infant death syndrome, and autism have not been substantiated by scientific studies.