Frequently Asked Question

1. What do immunizations do?

Ans. Vaccines work by preparing a child's body to fight illness. Each immunization contains either a dead or a weakened germ (or parts of it) that causes a particular disease.

The body practices fighting the disease by making antibodies that recognize specific parts of that germ. This permanent or longstanding response means that if someone is ever exposed to the actual disease, the antibodies are already in place and the body knows how to combat it and the person doesn't get sick. This is called immunity.

2. Will my child's immune system be weaker by relying on a vaccine?

Ans. No, the immune system makes antibodies against a germ, like thechickenpox virus, whether it encounters it naturally or is exposed to it through a vaccine. Being vaccinated against one disease does not weaken the immune response to another disease.

3. Will the immunization give someone the very disease it's supposed to prevent?

Ans. This is one of the most common concerns about vaccines. However, it's impossible to get the disease from any vaccine made with dead (killed) bacteria or viruses or just part of the bacteria or virus.

Only those immunizations made from weakened (also calledattenuated) live viruses — like the chickenpox (varicella) or measles-mumps-rubella (MMR) vaccine — could possibly make a child develop a mild form of the disease, but it's almost alwaysmuch less severe than the illness that occurs when someone is infected with the disease-causing virus itself. However, for kids with weakened immune systems, such as those being treated for cancer, these vaccines may cause problems.

The risk of disease from vaccination is extremely small. One live virus vaccine that's no longer used in the United States is the oral polio vaccine (OPV). The success of the polio vaccination program has made it possible to replace the live virus vaccine with a killed virus form known as the inactivated polio vaccine (IPV). This change has completely eliminated the possibility of polio disease being caused by immunization in the United States.

4. Why should I have my child immunized if all the other kids in school are immunized?

Ans. It is true that a single child's chance of catching a disease is low if everyone else is immunized. But your child is also exposed to people other than just those in school. And if one person thinks about skipping vaccines, chances are that others are thinking the same thing. Each child who isn't immunized gives these highly contagious diseases one more chance to spread.

This actually happened between 1989 and 1991 when an epidemic of measles broke out in the United States. Lapsing rates of immunization among preschoolers led to a sharp increase in the number of measles cases, deaths, and children with permanent brain damage. Even in the first half of 2008, the number of cases of measles in the United States more than doubled from comparable time periods in recent years. Most of the cases were among people who had not been vaccinated. Similar outbreaks of whooping cough (pertussis) struck Japan and the United Kingdom in the 1970s after immunization rates declined.

Although vaccination rates are fairly high in the United States, there's no reliable way of knowing if everyone your child comes into contact with has been vaccinated, particularly now that so many people travel to and from other countries. So, the best way to protect your child is through immunization.

5. Why should I subject my child to a painful shot if vaccines aren't 100% effective?

Ans. Few things in medicine work 100% of the time, but vaccines are one of the most effective weapons we have against disease — they work in 85% to 99% of cases. They greatly reduce your child's risk of serious illness (particularly when more and more people use them) and give diseases fewer chances to take hold in a population.

It can be difficult to watch kids get a shot, but the short-term pain is nothing compared with suffering through a potentially deadly bout of diphtheria, pertussis, or measles.

6. Why do kids who are healthy, active, and eating well need to be immunized?

Ans. Vaccinations are intended to help keep healthy kids healthy. Because vaccines work by protecting the body before disease strikes, if you wait until your child gets sick, it will be too late for the vaccine to work. The best time to immunize kids is when they're healthy.

7. Can immunizations cause a bad reaction in my child?

Ans. The most common reactions to vaccines are minor and include:

•redness and swelling where the shot was given


•soreness at the site where the shot was given

In rare cases, immunizations can trigger more serious problems, such as seizures or severe allergic reactions. If your child has a history of allergies to food or medication, or has had a problem with a vaccine previously, make sure to let the doctor know before any vaccines are given. Every year, millions of kids are safely vaccinated and very few experience significant side effects.

Meanwhile, research continually improves the safety of immunizations. The American Academy of Pediatrics (AAP) now advises doctors to use a diphtheria, tetanus, and pertussis vaccine that includes only specific parts of the pertussis cell instead of the entire killed cell. This vaccine, called DTaP, has been associated with even fewer side effects.