Immunizations: Questions Parents Ask

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What are vaccinations (immunizations)?

Vaccinations (immunizations) help protect your child from certain diseases. They also help reduce the spread of disease to others. Sometimes a vaccine doesn't completely prevent the disease. But it will make the disease much less serious if your child does get it.

Some vaccines are given only one time. Others are given in several doses over time. Most are given as shots.

Why is it important to get my child immunized?

Immunizations save lives. They are the best way to help protect you or your child from getting certain diseases that can be spread to other people (infectious diseases). And there are often no medical treatments for these diseases.

They also help reduce the spread of disease to others to prevent sudden outbreaks of the disease, called epidemics. Preventing the spread of disease is very important for people with weak immune systems. These people may not be able to get vaccines, or vaccines don't work well for them. Their only protection is for others to get vaccinated so illnesses are less common.

People sometimes ask if babies don't get natural protection from disease from their mothers. And during the last few weeks of pregnancy, mothers do give their babies some protection against disease. But it is only for diseases that the mother is protected against. The protection the baby gets doesn't last very long.

There are many other reasons why vaccines are important:

  • They cost less than getting treated for the disease.
  • The risk of getting a disease is much greater than the risk of having a serious reaction to the vaccine.
  • They are often needed for entrance into school or day care. And you may need them for your job or for travel to another country.
  • They prevent days out of work or school due to illness or caring for a sick person.
  • They may help stop preventable diseases from coming back.
  • If a disease occurs in a community, there is little or no risk of an outbreak if people have been immunized.

When should my child be immunized?

Immunizations start right after birth, and many are given throughout a baby's first 23 months. Booster shots occur throughout life. Booster shots are the later doses of any vaccines that need to be repeated over time.

Fewer vaccines are needed after age 6. But older children and teens need shots too. For example, they need a shot for bacterial meningitis and a shot for tetanus, diphtheria, and whooping cough. Some vaccines are also given during adulthood (such as the flu vaccine or a tetanus shot).

Talk to your doctor if you or your child plans to be in a group living situation, like a college dormitory or summer camp. You may need certain shots, like those for meningitis.

Why should I use the CDC immunization schedule? Can't I use my own schedule?

The U.S. Centers for Disease Control and Prevention (CDC) schedules are designed to work best with a child's immune system at certain ages and at certain times. They are set up so that your child gets the best protection possible at the earliest age possible from the fewest shots possible.

Why does my child need so many doses to protect against one disease?

You or your child gets as many shots as needed to give full protection from a disease. This may be just one shot. Or it may be several doses.

More than one dose may be needed because immunity may have to build up over time. You want the best mix of protection now and in the future. This means that you or your child needs a certain amount of vaccine spaced apart at different ages. This spacing builds the best protection.

Haven't we gotten rid of most diseases children are immunized for?

Immunizations in the United States have led to a sharp drop in diseases. Better living conditions have also helped. But this isn't enough to protect your child from disease.

A vaccine protects your child from the disease. A vaccine doesn't get rid of the disease. The disease still exists. And if fewer children get immunized for a disease, the disease could come back.

Is it okay to skip a shot when my child is sick?

You may worry that vaccines are dangerous if they're given when your child has a cold, an ear infection, or some other minor illness. But vaccines can usually still be given during a mild illness. They may also be given while the child is taking medicines (such as antibiotics, and in other cases where a child may not be in the best of health). There are very few reasons for which doctors suggest that someone postpone or not get a vaccine.

Very rarely, your doctor may suggest not getting a vaccine according to schedule. For example, you may need to wait when your child has:

  • A history of serious allergic reaction to a vaccine.
  • Severe vomiting or diarrhea, when dehydration is a concern.
  • A serious illness, such as pneumonia, or a severe asthma attack.

Talk to the doctor if you have concerns about giving your child a vaccine when your child doesn't feel well.

Vaccine Safety

Vaccines are studied for safety on an ongoing basis. The U.S. Food and Drug Administration (FDA) carefully checks all vaccines for safety. Other government agencies watch for reports of rare or unexpected reactions. Sometimes the area where the shot was given may be sore. And some children may be fussy. Or they may get a slight fever. Serious side effects are very rare. The greater risk lies in getting the illness.

Some parents worry that vaccines cause autism spectrum disorder (ASD) in children. But many studies have been done, and no link has been found between vaccines and ASD. Go to to follow a very large study about the risks for ASD and other developmental disabilities.

Getting more than one vaccine at a time

Getting more than one vaccine at a time is not dangerous.

Some parents worry about their children getting several vaccines at the same time. They worry that a child's immune system can't handle all those vaccines at the same time.

Getting more than one shot may seem like a lot for a child's body to handle. But babies have billions of immune system cells that are hard at work all the time, fighting the many thousands of germs they're exposed to every day.

After careful study, more and more vaccines are being combined into a single shot, such as the measles-mumps-rubella shot. This means you or your child needs fewer shots. Even though the vaccines are combined, each gives the same protection as it would if it were given alone.

The U.S. Advisory Committee on Immunization Practices and the American Academy of Pediatrics both recommend that a child get all of the vaccines needed at the child's age in one doctor visit.

Combination vaccines include:

  • Hepatitis B/Haemophilus influenzae type b.
  • Diphtheria, tetanus, pertussis/Polio.
  • Diphtheria, tetanus, pertussis/Polio/Hepatitis B.
  • Diphtheria, tetanus, pertussis/Polio/Haemophilus influenzae type b.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) continue to study vaccines. The risk of problems from vaccines is already extremely low. But these agencies watch for any reports of rare or unexpected reactions.

Talk to your doctor if you have concerns about the safety of vaccines.

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Current as of: June 12, 2023

Author: Healthwise Staff
Clinical Review Board
All Healthwise education is reviewed by a team that includes physicians, nurses, advanced practitioners, registered dieticians, and other healthcare professionals.

The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.