Guide
Catching up on vaccines at 3 years
A 3-year-old with no prior vaccines needs about 18 doses over as few as 8 visits (18 visits at one dose per visit), against 26 doses on the on-time schedule. No plan finishes before 4 years, because the last DTaP and polio doses wait for the 4th birthday, 12 months after the first visit.
Key takeaways
- Of the 26 on-time doses in these 8 vaccines, 18 are still needed at 3 years: DTaP 4 instead of 5, IPV 3 instead of 4, Hib 1 instead of 4 and PCV 1 instead of 4.
- From 3 years, 3 doses per visit takes 8 visits over 12 months, ending at 4 years; one dose per visit takes 18 visits over 20 months.
- Rotavirus is no longer possible: the final dose is due before 8 months and this child is 2 years 4 months past it.
- By 3 years, an on-time child would already have had 22 of these routine doses; this plan counts none of them as given.
Doses needed at 3 years, vaccine by vaccine
| Vaccine | On time | If started now | Planner minimum | Why |
|---|---|---|---|---|
| HepB (Hepatitis B) | 3 | 3 | 3 | No reduction. Gaps of 4 weeks and 8 weeks between doses. |
| DTaP (Diphtheria, Tetanus & Pertussis) | 5 | 4–5 | 4 | 4-dose delayed path (4th dose at age ≥4 replaces doses 4 & 5). |
| IPV (Polio (Inactivated)) | 4 | 3–4 | 3 | 3-dose delayed path (3rd dose at age ≥4 is the final dose). |
| Hib (Haemophilus influenzae type b) | 4 | 1 | 1 | Start 15–59 mo: a single dose completes Hib. |
| PCV (Pneumococcal Conjugate) | 4 | 1 | 1 | Start 24–59 mo (healthy): a single dose completes PCV. |
| MMR (Measles, Mumps & Rubella) | 2 | 2 | 2 | No reduction. Second dose at least 4 weeks after the first. |
| VAR (Varicella (Chickenpox)) | 2 | 2 | 2 | No reduction. Second dose at least 3 months after the first. |
| HepA (Hepatitis A) | 2 | 2 | 2 | No reduction. The two doses are at least 6 months apart. |
"If started now" and "Planner minimum" agree at 3 years. A range such as 4–5 means the lower number applies when the final dose is given at age 4 or later.
Visits and finish age
Starting at 3 years, three doses per visit needs 10 visits fewer than one at a time and ends 8 months sooner. The required gaps set the floor: the earliest plan ends 12 months after the first visit, at 4 years.
| Pace | Visits | Doses placed | Last visit at |
|---|---|---|---|
| 1 dose per visit, 1 month apart | 18 | 18 | 4 years 8 months |
| 3 doses per visit, 1 month apart | 8 | 18 | 4 years |
| Planner preset: one vaccine per visit, 2 months apart | 18 | 18 | 5 years 10 months |
Pace figures come from the same engine as the planner, with a healthy child, the planner's default vaccines and no prior doses.
Rules that apply at 3 years
- Rotavirus (RV) is not possible: its final dose must come before 8 months, which this child passed 2 years 4 months ago.
- At 3 years the planner uses 1 dose of Hib; the CDC bands are 3 doses if the first is at 7 to 11 months; 2 doses if the first is at 12 to 14 months; 1 dose if the first is at 15 to 59 months, and none from age 5.
- At 3 years the planner uses 1 dose of PCV; the CDC bands are 3 doses if the first is at 7 to 11 months; 2 doses if the first is at 12 to 23 months; 1 dose if the first is at 24 to 59 months, and none from age 5.
- At 3 years DTaP is 4 doses and polio 3: the last dose goes at age 4 or later and at least 6 months after the one before, which is 12 months after the first visit.
- At 3 years, hepatitis A needs 6 months between its two doses, the longest fixed wait in the plan.
- 3 years is 12 months short of age 4, so the planner's note applies: Give MMR and Varicella as separate shots before age 4 (lower febrile-seizure risk).
Questions parents ask at this age
How many vaccines does a 3-year-old need to catch up?
At 3 years the plan is 18 doses (HepB 3, DTaP 4, IPV 3, Hib 1, PCV 1, MMR 2, VAR 2, HepA 2) out of 26 on the on-time series, of which an on-time child has had 22 by now.
How many visits will a 3-year-old need?
From 3 years: as few as 8 with up to 3 doses per visit (finishing at 4 years), 18 with one dose per visit and 1 month between (4 years 8 months), or 18 on the planner's one-vaccine-per-visit preset with 2 months between (5 years 10 months).
Should a 3-year-old get MMR and varicella at the same visit?
Before age 4 the planner's note is: "Give MMR and Varicella as separate shots before age 4 (lower febrile-seizure risk)", meaning two injections rather than the combined MMRV shot; they can still share a visit. A 3-year-old is 12 months from that age. At 3 doses per visit the whole plan takes 8 visits.
How long does a 3-year-old have for Hib and PCV?
24 months, until the 5th birthday. A plan at one dose per visit runs until age 4 years 8 months, which is past that, so Hib and PCV (2 doses together) belong in the first visits.
Build the plan for 3 years
Enter the birth date and any doses already given; the planner counts them and spaces the rest.
Open the planner in catch-up mode One vaccine per visit Up to 4 per visitSources
Primary sources only. Links open the publisher's own page.