Guide

Who should not use this tool without clinician guidance

The planner builds a slower schedule for a healthy child using the CDC's minimum ages and intervals. Some situations change which vaccines, doses or timing are right, and in those cases a plan from this site should not be used unless your child's clinician has reviewed it.

By IN2Labs Last reviewed October 12, 2026 Sources: CDC, CRS Editorial policy

Key takeaways

The planner does not model medical conditions. The CDC schedule has a separate table of additional recommendations by medical indication.
Babies born to a mother who is hepatitis B surface antigen (HBsAg)-positive, or whose status is unknown, need hepatitis B vaccine within 12 hours of birth under the CDC schedule notes. Do not use a delayed plan for the birth dose in those cases.
Children with weakened immune systems generally should not receive live vaccines, and timing depends on their treatment.
A severe allergic reaction to a previous dose or a vaccine component is a contraindication. Travel and outbreaks can also change what is recommended.

Hepatitis B birth dose: mothers who are HBsAg-positive or whose status is unknown

Do not delay the first hepatitis B dose without your clinician's direction if the mother tests positive for hepatitis B or her status is not known at delivery.

Mother HBsAg-positive: the CDC schedule notes say to give hepatitis B vaccine and hepatitis B immune globulin (HBIG), in separate limbs, within 12 hours of birth, regardless of birth weight. Babies under 2,000 grams get 3 additional doses starting at 1 month (4 doses in total).
Mother's status unknown: for a baby of 2,000 grams or more, give the vaccine within 12 hours of birth and determine the mother's status as soon as possible; if she is HBsAg-positive, HBIG is given as soon as possible and no later than 7 days of age. Babies under 2,000 grams get vaccine and HBIG within 12 hours.
Testing: babies of HBsAg-positive or unknown-status mothers are tested for HBsAg and anti-HBs at 9–12 months (not before 9 months).

Why this matters: the CDC says about 90% of infected infants remain chronically infected, compared with about 30% of children infected between ages 1 and 5.

What changed in 2025–2026, and what did not

In December 2025 ACIP voted to recommend individual-based decision-making for the hepatitis B vaccine, including the birth dose, for infants born to women who test negative for the virus, with the initial dose no earlier than 2 months for infants who skip the birth dose (CDC release, Dec 5, 2025). The Congressional Research Service summarizes that ACIP continued the recommendation for a birth dose for infants born to mothers who test positive (CRS IN12684). CRS describes the vote as covering mothers with negative or unknown results, while the CDC's release describes mothers who test negative; we could not confirm the unknown-status wording from the CDC's own release, so check with your clinician.

On March 16, 2026 a federal court stayed the ACIP votes after June 11, 2025 and the January 2026 schedule (see CDC vs. AAP in 2026). The CDC schedule notes currently on the CDC's site are the July 2, 2025 version quoted above. Under either version, the recommendation for a birth dose for babies of HBsAg-positive mothers was not changed.

Weakened immune systems (immunocompromise)

The CDC says people with most forms of altered immunocompetence should not receive live vaccines, with listed exceptions, and that the degree of immunocompetence “should be determined by a physician.” Live vaccines include MMR, varicella and rotavirus. After certain treatments, live vaccines are deferred for a set time (for example, at least 1 month after high-dose corticosteroids and 2 months after anti-rejection therapy for a solid organ transplant). The CDC also says interpreting the effects of a drug or disease may require consultation with an infectious diseases or immunology specialist, and that close contacts should receive all age- and exposure-appropriate vaccines (CDC: Altered Immunocompetence). This planner does not model any of that.

Premature or low-birth-weight babies

The CDC lists preterm birth among conditions commonly misperceived as reasons to defer vaccination: it is generally not a valid reason to delay. Hepatitis B is the stated exception, where vaccination may be deferred for an infant under 2,000 grams only when the mother is documented as HBsAg-negative, and then it starts at 1 month of age or hospital discharge, whichever is earlier (CDC: Contraindications and Precautions; schedule notes). The planner works from your child's date of birth and does not take birth weight or gestational age into account, so ask your clinician which doses and ages apply.

Allergies and prior reactions

The CDC defines a contraindication as a condition that increases the risk of a serious adverse reaction, and a precaution as a condition that might. A severe allergic reaction (for example, anaphylaxis) after a previous dose or to a vaccine component is a contraindication for the vaccines the CDC page covers. Our ingredient guide lists what is in each product so you can bring a specific question to your clinician, but it cannot tell you whether a product is safe for your child.

International travel, outbreaks and moving between states

Travel and local outbreaks can change what is recommended. The CDC schedule notes give hepatitis A and MMR their own travel-specific schedules for infants and children, and point to the CDC Travelers' Health site. For any vaccine-preventable disease outbreak, the notes say to contact your state or local health department. A slower plan may leave a child unprotected on a trip or during an outbreak, so tell your clinician about plans well in advance.

Other situations that need a clinician

Chronic medical conditions (the CDC notes name examples such as asplenia and HIV): the CDC schedule has additional recommendations by medical indication.
Children who have missed many doses or whose records are incomplete.
Anyone who is unsure whether their child counts as “healthy” for these purposes.

The tool is free and stays on your device, but it is not a substitute for medical advice. Read the medical disclaimer and the pediatrician conversation guide.

Sources

Primary sources only. Links open the publisher's own page.