Background: Missed immunization opportunities (MOs) are a significant barrier to achieving high immunization coverage.
Objective: To describe the nature of MOs to immunize within primary care in New Zealand and their effect on immunization completeness.
Methods: Audit of medical records of approximately 10 randomly selected children <2 years old from each of 62 primary care practices in Auckland, New Zealand.
Results: The 616 audited children made 10 094 visits to primary care practices. MOs occurred at 97% (60) of practices, in 556 (5.5%) of visits, and 31% of the children had one or more visits that were an MO. Overall, children who had any recorded MO visit were 3.1 times more likely to be incompletely immunized than children who had no recorded MO (95% CI 1.87-5.14). Children with the greater percentage of overall visits that were MOs had up to a 9 times increased likelihood of incomplete immunization compared to those who had no MO visits. Nurse visits have less MOs than doctor (1.5% versus 6%) but are more likely to occur within well-child visits.
Conclusions: MOs are common in primary care practices, occurring in nearly one-third of visiting children. The risk of under-immunization increases with the increasing percentage of visits that are MOs. Overall strategies directed at reducing MOs need to focus on a range of aspects for the practitioner and the practice system.