The following are frequently-asked questions about the recommended childhood (up to 18 years old) and adult immunization schedules.
How are the childhood and adult immunization schedules determined?
The Centers for Disease Control and Prevention (CDC) sets the recommended immunization schedules for children, preteens/teens, adults, and pregnant women in the U.S. based on recommendations from the Advisory Committee on Immunization Practices (ACIP). The ACIP is a group of independent medical and public health experts who carefully review all available data about each vaccine from clinical trials and other studies in order to develop vaccine recommendations for children, adolescents and adults (including pregnant women).
Before making any recommendations, the ACIP reviews extensive research on the safety and effectiveness of each vaccine. The group’s recommendations include the age(s) when the vaccine should be given, the number of doses needed, the amount of time between doses, and precautions and contraindications. The ACIP examines both the safety and effectiveness of the vaccine given alone, as well as given in combination with other vaccines on the schedule. The ACIP meets three times a year to make recommendations for new vaccines and to make changes, if needed, to recommended vaccinations based on the latest science and research. (ACIP meetings are open to the public and can be viewed online via live webcast.) The recommended immunization schedules for all ages are reviewed and updated, if needed, every year.
The CDC’s Recommended Childhood Immunization Schedule (from birth to 18 years old) is the ONLY vaccination schedule for children and teens that is rigorously tested for safety and effectiveness.
- The CDC’s childhood schedule is also recommended by the leading medical groups in the U.S. including the American Academy of Pediatrics (AAP) and the American Academy of Family Physicians (AAFP).
- This CDC’s adult schedule is also recommended by the American College of Physicians (ACP), the American Academy of Family Physicians (AAFP), the American College of Obstetricians and Gynecologists (ACOG), the American College of Nurse-Midwives (ACNM), and American Academy of Physician Assistants (AAPA).
- The vaccines in the schedule are carefully timed to provide protection to your child when they are most vulnerable to, and before they are exposed to, dangerous diseases.
- The vaccines are recommended to be given when they will produce the strongest response from your child’s immune system.
How do they determine the ages when children should receive each vaccine? Is it okay to delay vaccines?
Where can I find the recommended immunization schedules for myself and my family?
See the recommended vaccine schedule for children birth through 6 years old by clicking here. Learn more about vaccines for babies and young children.
See the recommended vaccine schedule for children 7 through 18 years old by clicking here. Learn more about vaccines for preteens and teens.
See the recommended vaccine schedule for adults 19 years and older by clicking here. Learn more about vaccines for adults. Learn more about vaccines for pregnant people.
COVID-19 vaccines, which are recommended for people 5 and older, are not listed on the 2021 Recommended Immunization Schedules. To learn more COVID-19 vaccines and who is recommended to get them, visit our COVID Q&A page.
Why do we start vaccines so early?
The Centers for Disease Control and Prevention’s (CDC) recommended immunization schedule for children is specific, and with good reason. Vaccines are recommended for very young children because this is when they are most vulnerable to serious, life-threatening diseases. The recommended schedule is designed to protect your child by providing immunity early in life, before he or she is exposed to dangerous diseases, and when the vaccines will produce the strongest response from your child’s immune system. Delaying a child’s vaccinations just increases the time that he is susceptible to dangerous, and potentially life-threatening diseases.
As your child is growing and adapting to his new world, so is his or her immune system. From the time your baby is born, the immune system begins fighting off millions of germs (bacteria and viruses). Newborns may be immune to some infections because they’ve received antibodies from their mothers, but that protection begins to fade in the first months of life, leaving the baby vulnerable to infectious diseases. Even breastfed babies need to be protected with vaccines at the recommended ages. While breast milk provides important protection from some infections (colds, ear infections and diarrhea), it does not protect children against all diseases. Your baby needs the long-term protection that can only come from making sure he or she receives all his vaccines according to the CDC’s recommended immunization schedule.
Learn more about How Vaccines Work.
Download Too Many Vaccines? What You Should Know in English and Spanish from the Vaccine Education Center.
Why is it necessary to vaccinate infants who are so young?
Why does my child need so many vaccines at once?
Vaccines are given to infants to help save them from dangerous diseases when they are most likely to become severely ill or die from them. The recommended schedule is designed to protect your child by providing immunity early in life, before he or she is exposed to dangerous diseases, and when the vaccines will produce the strongest response from your child’s immune system.
Did you know that although children are vaccinated against more diseases now than ever before, the number of antigens in vaccines has actually substantially decreased? (Antigens are the substances that trigger your immune system to develop antibodies against the virus or bacteria.) Thirty years ago, children were only vaccinated against 8 diseases, and the total number of antigens was a little more than 3,000. Today, by age two, children are recommended to get vaccines that protect against 14 diseases, but the total number of antigens in these vaccines is only about 150. Vaccines contain just the necessary amount of antigens to help your child’s immune system fight off disease if he/she comes in contact with the virus or bacteria.
Extensive research has been conducted worldwide to ensure that multiple vaccines are safe for infants. These studies do not support the idea that multiple vaccines overwhelm or weaken your baby’s immune system. Learn more about How Vaccines Work.
Can vaccines overload my baby’s immune system?
No, vaccines will not overload your baby’s immune system. Extensive research has been conducted worldwide to ensure that multiple vaccines are safe for infants. These studies do not support the idea that multiple vaccines overwhelm or weaken your baby’s immune system. In fact, vaccines give your child just enough of the antibodies they need to fight off serious vaccine-preventable diseases. Even if your baby receives several vaccines in one day, they only contain a tiny fraction of the antigens that your baby encounters every day in his or her environment. Infants are fully capable of developing immune responses to multiple vaccines at the same time, in addition to responding to the many other challenges present in the environment.
Thirty years ago, children were only vaccinated against 8 diseases and the total number of antigens was a little more than 3,000. Today, by the age of 2, children receive vaccines that protect against 14 diseases, but the total number of antigens in these vaccines is only about 150. Learn more about this issue.
Sources: * Offit et al. Addressing Parents’ Concerns: Do Multiple Vaccines Overwhelm or Weaken the Infant’s Immune System? Pediatrics 2002 and CDC
“Are we overwhelming the immune system by giving too many vaccines?”
Why do some vaccines require more doses/shots than other vaccines?
Scientific research shows that for some vaccines, people need more than one dose to develop the best immune response. For example, after one dose of the measles, mumps and rubella vaccine (MMR), some people may not develop enough antibodies to fight off infection. The additional doses help make sure people are protected against the three diseases for as long as possible.
For other vaccines such as DTaP, which protects children against diphtheria, tetanus, and pertussis (also known as whooping cough), the initial series of four doses of DTaP helps children’s bodies build immunity (protection) against the three diseases. However, after a while that immunity begins to wear off and a “booster” dose is needed to bring immunity levels back up. For DTaP, the booster dose is needed for children between 4 and 6 years of age, and then another booster dose is needed at 11 or 12 years of age. The booster for older children (and teens, adults and pregnant women) is called Tdap.
Why do we vaccinate against diseases we rarely see?
Serious diseases are still out there. While parents today may have been spared from witnessing the devastating effects of diseases such as polio or measles, that does not mean these diseases are no longer here in the United States. In fact, each year there are disease outbreaks in communities across the U.S. Over the past few years, we have seen numerous outbreaks of whooping cough (pertussis), flu, measles and mumps in the U.S. Sadly, many of the families who have shared their stories after becoming seriously ill or losing loved ones also believed that the diseases were no longer a threat to their family members.
Many diseases are just a plane ride away and can spread easily, especially in today’s interconnected world. For example, in 2014, the United States experienced a large number of measles cases…667 people in 27 states. Many of the cases in the U.S. in 2014 were associated with cases brought in from the Philippines. In 2015, 188 people were reported as having measles in the U.S., and almost all of those measles cases were associated with international travel. Unfortunately, in 2019, the U.S. experienced the most number of measles cases since 1992. There were 1,281 cases of measles in 31 states, and just like in past years, these outbreaks were linked to travelers who brought measles back from other countries such as Israel, Ukraine, and the Philippines, where large measles outbreaks were occurring. Make sure you and your family members are vaccinated against measles and other infectious diseases like COVID-19, especially before traveling internationally. Find out what vaccines your family may need BEFORE traveling.
Learn more about measles, COVID-19 and other vaccine-preventable diseases.
What are combination vaccines and why are they used?
Combination vaccines take two or more vaccines that could be given individually and put them together into one shot. This way, people get the same protection as they do from individual vaccines given separately, but they get fewer shots. (And less shots usually mean less pain and stress from getting vaccinated.)
Examples of combination vaccines for children in the U.S. include:
- Pediarix – combines DTaP, Hepatitis B, and IPV (polio)
- ProQuad – combines MMR and varicella (chickenpox)
- Kinrix – combines DTaP and IPV
- Pentacel – combines DTaP, IPV, and Hib
The MMR vaccine (measles, mumps, and rubella) and the DTaP vaccine (diphtheria, tetanus, and pertussis) for young children, as well as the Tdap vaccine (tetanus, diphtheria and pertussis) for older children, pregnant women and adults, each protect against three diseases. However, these three vaccines are NOT called combination vaccines in the United States because you cannot get separate vaccines for all of the diseases that the MMR, DTaP, and Tdap vaccines protect against.
As with individual vaccines, before a combination vaccine is approved and recommended for use in the U.S., it goes through a lot of testing to make sure it is safe and effective. Sometimes combination vaccines cause slightly more pain or swelling where the shot was given. But if the vaccines were given individually, the person getting them could have pain or swelling in two or three spots, instead of just one. And just like for individual vaccines, safety systems are also in place after the combination vaccines are recommended to watch for very rare side effects.
What is the “non-standard” or “alternative” childhood schedule and is it safe? Is it safe for me to delay my child’s vaccines?
It is not safe to delay the vaccines for your children. While some parents may think using about “alternative” or “non-standard” vaccine schedules, it is important to understand that none of these other vaccination schedules have ever been tested for their safety and effectiveness, and so they can be dangerous for your children’s health. Please speak to your children’s healthcare provider and make sure you are making your decisions based on complete, science-based information.
Read The Problem with Dr. Bob’s Alternative Vaccine Schedule.
The CDC’s Advisory Committee on Immunization Practices (ACIP) develops the recommended immunization schedules for children, teens, adults (including pregnant women) in the U.S., and their recommended childhood immunization schedule is the ONLY vaccination schedule for children that is rigorously tested for safety and effectiveness. Therefore, it is very important to follow it as closely as possible. The vaccines in the recommended childhood schedule are carefully timed to provide protection to children when they are most vulnerable to diseases, and when they will produce the strongest response from their immune systems.
How do they determine the ages when children should receive each vaccine? Is it okay to delay vaccines?
Can’t I just wait until there is an outbreak or until my child goes to school to get their vaccines?
No, you should not wait until an outbreak or until your child is entering school to give him or her vaccines.
Before entering school, young children can be exposed to vaccine-preventable diseases from parents, grandparents, other adults, brothers and sisters, at daycare/preschool, or even at your local store. Children under age 5 are especially susceptible to diseases because their immune systems have not built up the necessary defenses to fight deadly infections. That’s why it’s very important to vaccinate your child on time.
By following the CDC’s recommended schedule, beginning with the hepatitis B vaccine – which is given to your baby before leaving the hospital – you are protecting your child from 14 serious diseases by the age of two. The vaccines in the recommended schedule are carefully timed to provide protection to children when they are most vulnerable to dangerous diseases, and when the vaccines will produce the strongest response from the immune system. Also, the recommended schedule protects children by providing immunity early in life, before they come into contact with life-threatening diseases.
How do they determine the ages when children should receive each vaccine? Is it okay to delay vaccines?
Should my child get a vaccine if they are sick or on antibiotics?
Even though your first instinct may be to cancel your child’s vaccination appointment when he or she has a cold, cough, ear infection, mild diarrhea, and/or low-grade fever (less than 101 degrees), experts at Centers for Disease Control and Prevention (CDC), American Academy of Pediatrics (AAP) and American Academy of Family Physicians (AAFP) agree that children with mild illnesses can still get vaccines and there are no health benefits to delaying vaccines. Vaccines do not make symptoms of an illness worse, even though they may cause mild side effects like a low fever, or soreness or swelling where the vaccine(s) was given. It is also fine for your child to get vaccinated if he or she is taking antibiotics for a mild illness since they won’t affect how your child’s body responds to the vaccines. So don’t delay. It’s very important for children get their vaccines on time in order to help protect them as soon as possible from serious diseases.
Your child’s healthcare provider can help you best determine if he or she should be vaccinated as planned, or if the appointment needs to wait.
My baby was premature, should I follow a different vaccination schedule
According to the American Academy of Pediatrics (AAP), preterm infants are at increased risk of experiencing complications from vaccine-preventable diseases, but are less likely to receive immunizations on time. However, all of these premature babies should get their vaccines according to the CDC’s recommended childhood immunization schedule.
The AAP states that parents of preterm babies who are concerned about vaccinating should keep the following issues in mind:
- If preterm babies get the infections that vaccines can prevent, they have a greater chance of having disease-related problems.
- All of the available vaccines are safe when given to preterm and low birth weight babies.
- Any side effects associated with the vaccines are similar in both full-term and preterm babies.
Who decides what vaccines my child needs for school?
Your state may require your child be vaccinated against certain diseases before entering daycare, preschool or school. Each state decides which vaccines are required for your child’s enrollment and attendance at a daycare/preschool or school in that state. Requirements may vary state by state.
Check with your child’s doctor, your child’s school, or your health department to learn about your state requirements.
Children with weakened immune systems and/or other specific medical conditions may get a medical exemption to the state’s vaccination requirement(s), usually with a doctor’s letter. These children, and other people with weakened immune systems, such as people with cancer or going through cancer treatment, depend on a high level of immunization in their daycares, schools and communities to protect them against vaccine-preventable diseases. This concept is known as community immunity and this is also why states have vaccine requirements. If people stop vaccinating their children, diseases that we once thought were gone or rare from the U.S. will come back. Without high levels of vaccinations, diseases can more easily spread in the community and put people of all ages at risk – even those who are healthy – of very serious illness.
My child was vaccinated ahead of schedule, now my child’s school/doctors are saying he needs another dose of the vaccine. Why is this? Is it safe?
Yes, it is safe for children to receive extra doses of vaccines. If your child received a vaccine before it was recommended their bodies may not have been able to build up a good enough immune response. For example, MMR (measles, mumps, and rubella) vaccine given before 12 months of age may not give a baby long-lasting immunity from all three diseases because your child may still have antibodies from you that trick their body into believing it is already protected. Also, if a child receives a second or third dose of a vaccine before the recommended time, it may not be as effective. This is why following the CDC’s recommended childhood immunization schedule is so important, as even the spacing/timing between doses is only recommended after the CDC’s ACIP carefully reviews all of the available vaccine research.
If your school or daycare has determined that your child needs additional vaccines because they were not vaccinated according to the recommended schedule and/or immunization laws in your state, please remember that they are only trying to make certain that your child and their classmates are protected from serious diseases that can spread to other people and make them very sick.