Enter the child's age and vaccines already received. Generate a catch-up framework with minimum intervals and next-dose planning for clinical review.
Check off each dose the child has received. Leave unchecked if not given or unknown.
A catch-up immunization schedule is a plan for children or adolescents who have missed one or more recommended vaccine doses. The AAP catch-up schedule specifies minimum ages, minimum intervals, and age-based dose requirements for each antigen.
The key principle is that vaccine series generally do not need to be restarted regardless of time elapsed between doses. Previously administered valid doses still count, and the catch-up plan focuses on remaining doses and valid spacing.
To determine catch-up needs: (1) identify the child's current age; (2) review documented vaccine history to count valid doses by antigen; (3) compare against the AAP-endorsed routine and catch-up schedule; (4) apply minimum interval rules to determine when each remaining dose can be given.
Important rules: doses given before the minimum age are usually invalid and may need repetition. A 4-day grace period may apply in select scenarios. Some vaccines (for example Hib and PCV) have age-at-first-dose dependent schedules.
Minimum intervals are the shortest acceptable time between doses of the same vaccine. They ensure adequate immune response. Common examples: DTaP doses 1-3 require a 4-week minimum interval, IPV doses have 4-week minimum intervals between early doses and 6 months before the final dose, and MMR doses require 4 weeks minimum between doses.
Administering vaccines too close together (shorter than the minimum interval) may reduce the immune response and the dose may be considered invalid. The general ACIP rule: if the interval was at least 4 days shorter than the minimum (the "4-day grace period"), the dose can still be counted as valid.
Yes. Multiple vaccines can and should be given at the same visit when a child is behind on schedule. This is consistent with AAP recommendations and national immunization administration guidance. Simultaneous administration does not reduce efficacy and is commonly used to accelerate catch-up.
Some considerations: Live injectable vaccines (MMR, Varicella) not given on the same day should be separated by at least 28 days. Combination vaccines can reduce injection burden. Clinical judgment and local policy still apply.
When a child starts a series late, the total doses needed may be reduced depending on age at initiation and prior valid doses. For example, a first Hib dose at 15 months or older in a healthy child can complete that series; PCV catch-up can also use fewer doses at older ages.
AAP-endorsed catch-up guidance applies age-specific rules by antigen, so dose count and interval requirements must be interpreted in context of the child's age and history.
School-entry vaccine requirements vary by state, but most states require proof of immunization for DTaP/Tdap (diphtheria, tetanus, pertussis), IPV/OPV (polio), MMR (measles, mumps, rubella), Varicella (chickenpox or evidence of immunity), and Hepatitis B. Many states also require Hepatitis A and Meningococcal vaccines.
Children who are behind on vaccines can still attend school in most states with a provisional enrollment plan showing they are in the process of catching up. Medical, religious, or philosophical exemptions vary by state. The catch-up calculator helps identify exactly which doses are still needed to meet school entry requirements.