Cartoon image of a man showing his arm where he received a vaccination


The timing of events on the Immunisation Schedule and minimum intervals between the administration of catch-up vaccine doses is balanced by the ability of the vaccinee’s immune system to respond robustly to the vaccine antigens and develop protection against the disease(s) as soon as possible before risk of disease exposure.

Before vaccine doses are administered early, the potential effect on the immune response and level of protection the vaccinee develops after completing their course of vaccines must be considered.

The Immunisation Advisory Centre (IMAC) does not recommend vaccines being given earlier than their due dates. However, to allow for opportunistic immunisation rather than ask a parent to come back another time, there is a small amount of flexibility with the Immunisation Schedule (*see tables included in factsheet). We recommend that immunisation pre-call letters and texts include the date the immunisation event is due to reduce the possibility of parents making an appointment or visiting the practice too early.

IMAC acknowledges the increasing complexity of both the Immunisation Schedule and also catch-up immunisations. We strongly recommend that if you have any vaccine timing concerns or questions you discuss these with either your local immunisation coordinator or the IMAC clinical advice line 0800 466 863.

If a vaccinator notices an error in timing of vaccine administration e.g. earlier than generally accepted, advice should be sought from either their local immunisation coordinator, the IMAC clinical advice line 0800 466 863, practice management system referral or by emailing the details to This occurs frequently with overseas immunisation schedules.


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Last updated:
Jun 2023