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Project earliest, typical, and catch-up calendar dates from a last dose or date of birth using static templates for HPV, MMR, varicella, Hep B, coarse COVID-19 mRNA, and Tdap decade reminders. Pair with flu risk screening. Not IIS forecasts—not legal immunization records.
Last updated: June 5, 2026
Official due dates come from registries and clinicians. Verify every output against CDC schedules and your medical record.
Reference: date of the prior relevant dose.
Earliest (min spacing)
Sat, Jun 29, 2024
Typical target
Wed, Jul 31, 2024
Outer bound (if modeled)
Thu, Nov 28, 2024
From your reference dose date, the selected teaching template places the next step earliest on 2024-06-29, commonly around 2024-07-31, with a coarse outer planning bound near 2024-11-28.
Template note
Many schedules allow dose 2 as early as 4 weeks; some use 6- or 12-month spacing depending on age at start—confirm with your national immunization schedule.
Vaccine hesitancy, allergy work-up, and special populations need clinician and pharmacist input—never rely on a static web template for legal or medical decisions.
HPV dose 2 — ref 2024-06-01
2024-06-29
Earliest — typical 2024-07-31
MMR dose 2 — ref 2025-03-15
2025-04-12
+28 days minimum spacing
Hep B dose 2 — DOB 2025-11-01
2025-12-27
Typical +56 days from birth
COVID mRNA dose 2 — ref 2024-01-10
2024-02-07
Typical +28 days (teaching)
Varicella dose 2 — ref 2023-08-01
2023-10-24
Typical +84 days (~3 mo)
Tdap ~10 yr — ref 2014-09-20
2024-09-17
Decade booster teaching
Static teaching offsets — verify against current CDC/WHO footnotes.
| Template | Reference | Min | Typical | Outer |
|---|---|---|---|---|
| HPV dose 2 | Last dose 1 date | 28 days | 60 days | 180 days |
| HPV dose 3 | Last dose 1 date | 168 days (~6 mo) | 180 days | 366 days |
| MMR dose 2 | Last dose 1 date | 28 days | 28 days | 10 years (teaching) |
| Varicella dose 2 | Last dose 1 date | 28 days | 84 days (~3 mo) | 10 years (teaching) |
| Hep B dose 2 (pediatric) | Date of birth | 28 days | 56 days | 90 days |
| COVID mRNA dose 2 | Last dose 1 date | 21 days | 28 days | 56 days |
| Tdap/Td booster | Last Td-containing dose | ~9 years | ~10 years | ~12 years |
| Type | Templates | Common mistake |
|---|---|---|
| Last dose date | HPV, MMR, varicella, COVID, Tdap booster | Using DOB instead of prior shot date |
| Date of birth | Hep B dose 2 pediatric teaching row only | Using birth date for dose 2 after dose 1 |
| Aspect | IIS / EHR | This calculator |
|---|---|---|
| Data source | Coded vaccine history (CVX), lot, site, VIS date | Single static template + one reference date |
| Forecast logic | Rules engine with ACIP updates, age, contraindications | Fixed day offsets (min / typical / outer) |
| Legal use | School, employer, registry documentation | Classroom / caregiver orientation only |
| Product specificity | Brand, formulation, combination products | Generic teaching bands (e.g., mRNA COVID) |
| Vaccine | Rule | Note |
|---|---|---|
| MMR | ≥28 days between live doses if not same visit | This tool does not block same-day other vaccines |
| Varicella | Often ≥3 months between doses (child schedules) | Combined with MMR timing in some clinics |
| Live + IG | May need delay after immunoglobulin | Not modeled here — specialist guidance |
| Situation | Action | Example |
|---|---|---|
| Missed typical window | Many series continue without restart — clinician confirms | HPV dose 2 at 4 months still valid in many schedules |
| Very late dose | Catch-up tables exist per antigen in CDC footnotes | Adolescent starting HPV at age 15 may need 3 doses |
| Immunocompromised | Extra doses, different products — not this calculator | Extra COVID doses per immunocompromised guidance |
From your reference dose date, the selected teaching template places the next step earliest on 2024-06-29, commonly around 2024-07-31, with a coarse outer planning bound near 2024-11-28.
Educational disclaimer: This calculator applies static spacing templates for learning and caregiver orientation. It is not an immunization information system forecast, legal school documentation, or clinical order. Verify every date with CDC schedules, your state IIS, and your clinician or pharmacist.
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