In general, follow the recommendations in the manufacturers’ data sheets.
The immune response to a series of vaccines depends on the time interval between doses. A second dose of the same vaccine given less than three weeks from the first dose may result in a reduced immune response. Therefore, the general rule is for a minimum of four weeks between doses of a primary series, unless there are specific recommendations for a rapid schedule by the manufacturer. It is not necessary to repeat a prior dose if the time elapsed between doses is more than the recommended interval.
A minimum interval of four months between priming dose(s) and the booster dose allows affinity maturation of memory B cells, and thus higher secondary responses.
Unless the manufacturer makes a speciﬁc recommendation against it, an inactivated or subunit vaccine can be administered either simultaneously or at any time before or after a different inactivated or live vaccine.
Where two or more parenterally or intranasally administered live vaccines are given at different visits, a minimum interval of four weeks is recommended. This is to avoid the response to the second vaccine being diminished due to interference from the response to the first vaccine. Note that no interval is required between administration of BCG and rotavirus vaccines.
Best practice is to follow the Schedule. Changing the timing of visits or increasing the number of visits to avoid multiple injections may lead to incomplete immunisation.
Children without a documented history of vaccination are recommended to have a full course of vaccination appropriate for their age. In cases of doubt, it is much better to provide an unnecessary dose than to miss out a needed dose.
The objective of a catch-up programme is to complete a course of vaccinations which provides adequate protection. Catch-up programmes should be based on documented evidence of previous vaccination (eg, the child’s Well Child Tamariki Ora My Health Book or the NIR).
When children have missed vaccine doses, it is important to bring them up to date as quickly as possible. Where more than one vaccine is overdue, it is preferable to give as many as possible at the first visit. For children aged 15 months and older, MMR is the priority.
If the vaccinator is uncertain about how to plan a catch-up programme, they should contact the local immunisation coordinator, medical ofﬁcer of health, public health service or IMAC.
Once catch-up is achieved, the child should continue as per the Schedule.