About Immunizations and Vaccines

Immunization is a process of becoming protected from a disease or illness by receiving either a vaccine or preventive antibodies. Both vaccines and preventive antibodies may be called immunizations, but they work differently. Vaccines are used to stimulate a person's immune system to produce antibodies, while preventive antibodies are given directly to a person.

Why Immunizations are Important

Babies, children, and teens need immunizations to

• Teach or prepare the immune system to recognize germs (virus or bacteria) so their body knows how to respond if they are exposed to germs. Immunizations help the immune system build up its own long-term protection to diseases.

• Protect them from germs that can spread easily from person to person.

• Protect others from germs that can spread easily. This may be referred to as community immunity.

• Keep them safe and healthy as they grow so they can

  • Play with friends.

  • Sleep well and feel rested.

  • Stay in school and keep learning.

  • Participate in sports and other activities.

Safety and Effectiveness of Immunizations

Here's what you need to know about immunization safety and effectiveness.

• Immunizations work very well. Millions of children have been protected against serious illnesses because they were immunized. Most childhood immunizations are 90% to 99% effective in preventing disease. Children who aren't immunized are much more likely to get a disease if they are exposed to it. And if an immunized child gets the disease, the symptoms are usually milder with fewer complications than in a child who hasn't been immunized.

• The safety and effectiveness of immunizations are under constant study. Immunizations are designed to be given routinely during well-child visits. Safety testing begins as soon as a new immunization is considered, continues until it is approved by the US Food and Drug Administration (FDA), and is monitored indefinitely after licensure. The AAP works closely with the Centers for Disease Control and Prevention (CDC) to make recommendations for use of immunizations.

• Immunizations do not cause autism spectrum disorder (ASD). Many research studies have been done to address this issue. There may be confusion because children with ASD are often diagnosed between 18 and 30 months of age—around the same time the MMR vaccine is given. This has led some people to assume that the vaccine is the cause. Increasing evidence shows that even though the symptoms of ASD may not be visible until the second year after birth or later, ASD starts before a baby is born.

• There may be mild side effects, such as swelling, redness, and tenderness where the shot was given, but they do not last long. Your child may also have a slight fever and be fussy for a short time afterward. Your doctor may suggest giving your child pain medicine to help relieve discomfort. It is very rare for side effects to be serious. However, you should call your child's doctor if you have any concerns after immunizations are given.

Recommended Immunizations

Here are recommended childhood immunizations.

• RSV immunization to help prevent serious respiratory syncytial virus infection.

• Hepatitis A and hepatitis B vaccines to help protect against serious liver diseases.

• Rotavirus vaccine to help protect against the most common cause of diarrhea and vomiting in infants and young children. Rotavirus is the most common cause of hospitalizations in young infants due to vomiting, diarrhea, and dehydration.

• DTaP and Tdap vaccines to help protect against diphtheria, tetanus (lockjaw), and pertussis (whooping cough).

• Hib vaccine to help protect against Haemophilus influenzae type b (a cause of spinal meningitis and other serious infections).

• Pneumococcal vaccine to help protect against bacterial meningitis, pneumonia, and infections of the blood.

• Polio vaccine to help protect against a crippling viral disease that can cause paralysis.

• Influenza vaccine to help protect against influenza (flu), a potentially fatal disease. This vaccine is recommended for all people beginning at 6 months and older.

• COVID-19 vaccine to help protect against COVID-19.

• MMR vaccine to help protect against measles, mumps, and rubella (German measles), all highly contagious and potentially very serious diseases.

• Varicella vaccine to help protect against chickenpox and its many complications, including flesh-eating strep, staph toxic shock, and encephalitis (an inflammation of the brain).

• Meningococcal vaccine to help protect against very serious bacterial diseases that affect the blood, brain, and spinal cord.

• HPV (human papillomavirus) vaccine to prevent cancers of the mouth and throat, cervix, and genitals.

It's important to follow the schedule recommended by the AAP and CDC. Contact your child's doctor if you have any questions. (Parents, including expectant parents, should also make sure their immunizations are current.)

For More Information

It's important to make sure your immunization information sources are reliable and accurate including