U.S. vaccine schedule guides
The United States has two published childhood immunization schedules: the CDC and ACIP chart written for clinicians, and the American Academy of Pediatrics’ own version. Both list the same dozen vaccines from birth through age 18, organized by visit. These guides walk through that chart one age at a time: the 2, 4 and 6-month shots, the 12-month visit, kindergarten requirements, the teen doses at 11, 12 and 16, and what a catch-up schedule means when a dose was missed. Every guide links to the CDC or AAP page it draws from and shows a Published date and, once revised, an Updated date. None of it replaces your pediatrician, who sees your child and the chart together.
U.S. schedule · 20 guides
Minimum intervals: why the next dose cannot always be tomorrow
A clinic that moves a date is usually applying a minimum interval rule. What CDC says about spacing, early doses and why exact dates belong in a record.
How to Read the CDC Catch-Up Schedule Without Panicking
A missed dose is not a restart. Here is what the CDC catch-up schedule is for, who reads it, and what a parent should bring to the appointment instead.
The 11 to 12-Year-Old Visit: The Adolescent Vaccine Checkpoint
The preteen vaccine visit is the checkpoint the adolescent schedule is built around. Here is how to read it and keep follow-up doses from slipping.
The 4-Year-Old Shots: The Pre-Kindergarten Round, Explained
The 4 to 6-year window is when several childhood series get a booster. Here is what the CDC chart shows and how it relates to a school district form.
The 15 to 18-Month Window: The Doses That Finish a Series
Between 15 and 18 months several vaccine series get a last dose. Here is why the CDC schedule shows a window instead of a date, and what to track.
The 12-Month Visit: MMR, Varicella, Hepatitis A and What to Write Down
The 12-month visit often brings several vaccines at once. Here is how to read that column of the CDC schedule and what to note down before you leave.
Hib and PCV: The Infant Vaccine Schedules
CDC gives Hib at 2, 4, 6 if needed and 12-15 months, with PCV on a parallel infant series. How to read both lines on an after-visit summary.
Rotavirus Vaccine: The Age Window
CDC gives the first rotavirus dose before 15 weeks and the last before 8 months. Why that window is strict, and what a missed visit really means.
Polio Vaccine (IPV): Doses and Travel
IPV is the only polio vaccine used in the U.S. since 2000. How the childhood series is built, how OPV records read, and when travel reopens the question.
Chickenpox Vaccine: How Many Doses?
Two varicella doses are the U.S. routine, MMRV combines it with MMR, and a parent's own case of chickenpox is not documentation a school can file.
Hepatitis B Birth Dose: What Changed
The federal recommendation for the hepatitis B birth dose changed in 2026 while the AAP kept it universal. What both say, and what to write down.
MenACWY vs MenB: Which Does a Teen Need?
MenACWY at 11-12 with a booster at 16; MenB is a separate product decided case by case. How to fill a camp or college form without guessing.
HPV Vaccine at 11 or 12: Why So Early
Why pediatricians raise HPV vaccination at 11-12, how dose count depends on the age at first dose, and how to talk about it at home without a lecture.
MMR Vaccine: When, How Many Doses
CDC gives MMR at 12-15 months and 4-6 years. Two doses are 97% effective against measles. What MMRV means, and when travel changes the timing.
DTaP vs Tdap: What Is the Difference?
DTaP is the childhood formula, Tdap the adolescent and adult one, and Td has no pertussis. How to tell them apart on a record and on a form.
Catch-Up Vaccines: Missed a Dose?
A missed vaccine dose almost never means restarting the series. How the CDC catch-up schedule works, what to gather first, and what not to guess.
Kindergarten Vaccine Requirements by State
Kindergarten entry rules are set by states, not the CDC. What to gather, which 4-to-6-year doses come up, and the 2025-26 CDC coverage numbers.
The 2, 4 and 6 Month Shots Explained
What the 2, 4 and 6 month well-child visits cover, why the same vaccines repeat, and how to check the after-visit summary before you drive home.
Baby Vaccine Schedule: The First Year
Which vaccines U.S. babies receive in the first 12 months, why the visits cluster at 2, 4, 6 and 12 months, and what to write down each time.
CDC vs AAP Vaccine Schedule 2026
How the CDC and AAP childhood immunization schedules differ in 2026, how to read either chart by age, and which one your pediatrician follows.
Questions this section answers
One question from each guide above, answered here. Follow a question to the guide that works through it in full.
- Why can a clinic refuse to give a dose early?
Because a dose given before the minimum age or minimum interval may not count. CDC's timing and spacing guidance states that doses "administered too close together or at too young an age can lead to a suboptimal immune response," and that doses given more than four days early are not considered valid. Repeating an invalid dose later means an extra needle, so most clinics move the appointment instead.
Minimum intervals: why the next dose cannot always be tomorrow →- Does a missed dose mean starting the series over?
No. The CDC catch-up schedule states that "a vaccine series does not need to be restarted, regardless of the time that has elapsed between doses." A gap of years does not erase the doses already given; the practice resumes from where the record stops, using the minimum intervals in that document. What can force a dose to be repeated is a different problem — a dose given earlier than the minimum age or interval may not count.
How to Read the CDC Catch-Up Schedule Without Panicking →- Why is the preteen vaccine visit treated as a checkpoint?
Because the CDC chart has no routine vaccine band between 4 to 6 years and 11 to 12 years, the preteen visit is the first scheduled chance in roughly five years to compare a child's record against the schedule. It is where adolescent series start, where unfinished childhood series surface, and where doses due at later ages get planned. The chart is built around it being kept.
The 11 to 12-Year-Old Visit: The Adolescent Vaccine Checkpoint →- Are the 4-year-old shots the same as the school requirements?
Not necessarily. The CDC schedule is national medical guidance organized by age band; a school immunization list is written under state law and organized around an enrollment date. They usually overlap heavily, because most states build their lists from the same recommendations, but the wording, the dose counts requested and the deadlines can differ. Read the district packet as its own document and check it against your dated record.
The 4-Year-Old Shots: The Pre-Kindergarten Round, Explained →- Why does the schedule show a window rather than one date?
Because the recommendation is an age range in which a dose is expected to work as intended, not an appointment. The CDC chart draws DTaP dose four across 15 through 18 months, and hepatitis B and polio dose three across 6 through 18 months. A child vaccinated anywhere inside a band is on time, which is why two children the same age can carry different-looking records without either being behind.
The 15 to 18-Month Window: The Doses That Finish a Series →- How many shots are given at the 12-month visit?
There is no fixed number, and the CDC chart does not name one. Seven vaccine lines have bands open at or near twelve months, but some may already be complete, some may be held to the 15-month visit, and a combination product such as MMRV can put four disease names into a single injection. Two to four injections is the common range. The practice decides on the day.
The 12-Month Visit: MMR, Varicella, Hepatitis A and What to Write Down →- Is Hib the same as the flu vaccine?
No. Hib stands for Haemophilus influenzae type b, a bacterium named before anyone understood what caused influenza. The seasonal flu vaccine targets influenza viruses and is given every year. Hib is a bacterial vaccine given as an infant series ending at 12 through 15 months. A child needs both, and they appear on separate rows.
Hib and PCV: The Infant Vaccine Schedules →- Does spitting out the dose mean it does not count?
Not necessarily, and it is not a parent's call. Tell the nurse before you leave the room, and make sure the after-visit summary shows what was recorded. The CDC's rotavirus vaccination page and the clinician's own product guidance govern whether a partial dose is repeated. A dose you never mentioned is a dose nobody can assess later.
Rotavirus Vaccine: The Age Window →- Do adults need a polio booster?
Most grown-ups vaccinated as children in the United States are not routinely revaccinated. The CDC describes one lifetime booster dose of IPV for people who are fully vaccinated but at increased risk of exposure to poliovirus, which includes some travelers and some occupational settings. Whether that applies to you is a question for a clinician who can see your record, not a rule to apply from a destination page.
Polio Vaccine (IPV): Doses and Travel →- Can breakthrough chickenpox happen after vaccination?
Yes, and the CDC describes it as usually mild: "If a vaccinated person does get chickenpox, called breakthrough chickenpox, the symptoms are usually mild. Vaccinated people often experience fewer to no blisters and low or no fever, but red spots may occur." That is a description of what has been observed, not a diagnosis to make at home from a photograph.
Chickenpox Vaccine: How Many Doses? →- Does a mother's hepatitis B test result change the recommendation?
Maternal hepatitis B surface antigen testing has long been part of prenatal care and of what a delivery team acts on, and the CDC runs a Perinatal Hepatitis B Prevention program for exactly that reason. What a specific result means for a specific newborn is decided by the obstetric and pediatric team with the chart in front of them, not by a general article, and not by a parent reading a schedule.
Hepatitis B Birth Dose: What Changed →- Is "the meningitis shot" MenACWY or MenB?
Usually MenACWY, because that is the one the CDC recommends for all preteens at 11 to 12 with a booster at 16. But the phrase is ambiguous, and MenB is a separate product given preferably at 16 through 18. Settle MenACWY vs MenB by reading the letters on the record before answering a form; the two are not interchangeable and cannot substitute for each other.
MenACWY vs MenB: Which Does a Teen Need? →