The childhood immunisation schedule, age by age

Why the schedule has stages, not a single visit

A child's immune system develops in a predictable order, and the immunisation schedule is built around that development rather than around convenience. Doses are spaced apart because giving a vaccine too early can produce a weaker, shorter-lived response — the body simply isn't ready to build full protection yet — and giving several doses of the same vaccine at intervals, rather than one dose, is what actually produces long-term immunity for many of the vaccines on the schedule.

In broad terms, the first year of life carries the heaviest load of doses, because it covers protection against the diseases that pose the greatest risk to very young infants. The second year adds booster doses that reinforce what the first-year doses started. From around school-entry age onward, boosters continue at longer intervals, because immunity from earlier doses gradually wanes and needs reinforcing before it drops low enough to matter.

What's roughly due, age by age

Birth to six weeks: the earliest doses are given at or shortly after birth, protecting against diseases that carry the highest risk in the first weeks of life.

Six weeks to six months: this is the busiest window on the schedule. Several vaccines are given in a series of doses, spaced roughly a month apart, building layered protection during the period when an infant's own immune system is least developed.

Nine months to two years: a further round of doses and boosters follows, consolidating the protection built in infancy and adding coverage for diseases that become a more relevant risk as a toddler starts moving around, in nursery, and in contact with other children.

Four to six years and onward: booster doses at school-entry age, and further boosters through the school years and into adolescence, are what keep protection current as earlier immunity fades and a child's exposure to the wider world grows.

This is a general shape, not a fixed timetable for any individual child — the right schedule for a specific child depends on their exact age, what they've already had, and their health history, which is exactly why it is reviewed in person rather than read off a chart.

Why a dose is sometimes held back on the day

Parents are sometimes surprised when a vaccine they expected isn't given on the day they walk in, and it is worth explaining why that happens rather than leaving it unexplained. A vaccine given outside its recommended interval from the previous dose, or given to a child whose catch-up schedule has not been reviewed, can either under- protect the child or, in some cases, cause a reaction that a correctly timed dose would not. Before giving a dose — particularly a booster, or a vaccine a child is receiving later than the usual age — a doctor needs to confirm exactly which doses a child has already had, when, and whether anything in their recent health means a short delay is the safer choice.

That is a clinical judgement, made by looking at the child's own record, not a formality that can be skipped because a parent is confident the dose is due. A conservative, careful approach to timing is the same principle behind this clinic's approach to antibiotics: giving exactly what is needed, when it is genuinely the right time to give it, rather than on request. It can feel like an inconvenience in the moment, especially when you've made a special trip, but it is the same reasoning that keeps a vaccination schedule safe and effective in the first place — and it is why bringing a child's existing vaccination record along, if you have one, makes that on-the-spot review much faster.

What to bring

If your child has any previous vaccination record — a card, a hospital printout, or even a photo of one — bring it. It is the single fastest way for the clinic to confirm what's already been given and what's due next, without relying on memory alone.