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Frequently Asked Questions (FAQs)

IEL FAQ: What Do Parents Need to Know About Immunizations? About

Why should my child be immunized?

A baby will acquire antibodies to some diseases from his mother’s body before birth and from her milk as long as he is breastfed. But he is still vulnerable to many infections, and the passive immunity from his mother disappears quickly.

Some illnesses may seem like a normal part of childhood. Grandparents may remember having mumps, measles, or chickenpox. Many of us have had flu. However, some children who suffer these illnesses die or develop lifelong complications, such as the type of deafness or infertility that can be caused by mumps. Of every 1,000 children who get measles, one or two will die from the disease. Haemophilus influenzae type b (Hib) infection can cause the epiglottis in the throat to swell, cutting off a child’s ability to breathe. Before there was an effective vaccine, Hib struck about 1 in 200 children under the age of 5. It killed many children and often left survivors with permanent brain damage. After the Hib vaccine was introduced in the mid-1980s, the incidence of Hib dropped by 99%. Vaccines prevent many such diseases that once harmed and killed children. In addition, research published in 2011 suggests that the risk of SIDS is reduced by 50% in immunized infants.

Although the chances of a child coming into contact with one of these diseases has decreased because of vaccinations, the viruses and bacteria still exist and can be carried quickly in our mobile society. Every year in the United States, there are outbreaks of some of these diseases; these diseases can spread easily among children or adults who have not been immunized. An outbreak of Hib in 2008 in Minnesota made 5 children sick, and 1 died from the disease. From January 1 through May 20, 2011, 23 states (including Illinois) reported a total of 118 cases of measles.

In addition to protecting the individual child, high vaccination rates protect communities by slowing or stopping the spread of disease. Stopping the spread of disease helps protect those who cannot be vaccinated because they are too young, too old, or too sick. A high vaccination rate in the community also helps prevent birth defects that may be caused when a pregnant woman is infected.

How do immunizations prevent illness?

From birth, a healthy child’s immune system fights invading antigens. Antigens are the molecules on the surface of germs that stimulate the immune system to produce antibodies. A healthy immune system produces thousands of specific antibodies every day to fight specific antigens. Some antibody cells remain in the body and become "memory cells." If the same bacteria or virus tries to infect the body, memory cells defend against it. This person now has developed immunity to this disease. If the body has no memory cells, some bacteria or viruses can cause severe illness before the immune system can produce the antibodies to fight it.

Vaccines protect children by helping their bodies make antibodies against specific diseases. Vaccines are made using the killed or weakened antigens, or parts of them, that cause disease. Vaccine antigens are designed to alert the immune system to produce antibodies against a disease without causing the disease. The antibody memory cells remain to react quickly if they encounter the disease in the future. Vaccination leads to immunity without the child having to suffer from the actual disease.

Can vaccines harm my child?

Each new vaccine goes through several phases of testing, including clinical testing in volunteers, before it is approved by the Federal Drug Administration (FDA). The third phase involves testing in at least 10,000 people, and this stage lasts up to 4 years. The vaccine must be proven to be both safe and effective before it can be licensed for general use. Vaccines that are being used are monitored by the Immunization Safety Office of the Centers for Disease Control (CDC) through programs such as the Vaccine Adverse Event Reporting System (VAERS).

Immunizations, like any medication, can have side effects. A health care provider should be familiar with a child’s medical history before giving an immunization. For most children, the side effects may include a mild fever and soreness at the site of the vaccination. A very few children out of the millions vaccinated will have more serious problems, such as seizures or severe allergic reactions.

Extensive research studies have found no relationship between vaccines and autism spectrum disorders (ASDs). In 2010, Lancet, a widely trusted medical journal, reported that the research report that linked the two had been discredited, and the researcher was cited for unethical behavior. The records of the 12 cases cited in the discredited report were found to have been altered and misrepresented.

Not immunizing your child leaves him unprotected against diseases that can be dangerous or deadly. It also puts others at risk. Meanwhile, research continually improves the safety of immunizations.

Is it harmful for my baby to get so many vaccines so quickly?

Babies come into contact with many germs from breathing, eating, and interacting with people. A healthy infant’s immune system helps keep him well by reacting to 2,000-6,000 antigens every day. The whole schedule of recommended immunizations includes just 150 antigens, so getting several vaccines in a short period should not be too hard for children’s immune systems. It is important to work with your child’s doctor to determine if the standard immunization schedule is appropriate for your child. Some vaccines can be combined to help protect against more than one disease with fewer shots. Sometimes there’s a good reason to delay or not give certain vaccines to a child.

What immunizations do my children need?

The CDC recommends that children be immunized against diphtheria, pertussis, tetanus, polio, measles, mumps, rubella, flu, Haemophilus influenzae type b (Hib), hepatitis A and B, chickenpox, pneumococcal diseases, and rotavirus.

In Illinois, parents of children 2 months old and older who are entering a child care facility need to show proof that the children have been or are in the course of being immunized, as suggested in the state’s immunization schedule, against diphtheria, pertussis, tetanus, polio, measles, mumps, rubella, Haemophilus influenzae type b (Hib), hepatitis B, and varicella (chickenpox).

In Illinois, parents of children entering public school programs, including nursery schools, preschool programs, early childhood programs, Head Start, or other prekindergarten child care programs, need to show proof that their children have been immunized against diphtheria, pertussis, tetanus, polio, measles, mumps, rubella, Haemophilus influenzae type b (Hib), hepatitis B, and varicella (chickenpox). There are exceptions in the Illinois code. Parents should check with their child’s health care provider and preschool program.


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The opinions, resources, and referrals provided in this FAQ are intended for information purposes only and should not be considered or used as a substitute for medical advice, diagnosis, or treatment. We advise parents to seek the advice of a physician or other qualified health care provider with questions regarding their child’s health or medical conditions.


The opinions, resources, and referrals provided on the IEL Web site are intended for informational purposes only and are not intended to take the place of medical or legal advice, or of other appropriate services. We encourage you to seek direct local assistance from a qualified professional if necessary before taking action.

The content of the IEL Web site does not necessarily reflect the views or policies of the Illinois Early Learning Project, the University of Illinois at Urbana-Champaign, or the Illinois State Board of Education; nor does the mention of trade names, commercial products, or organizations imply endorsement by the Illinois Early Learning Project, the University of Illinois at Urbana-Champaign, or the Illinois State Board of Education.