Immunization Milestones: A More Comprehensive Picture of Age-Appropriate Vaccination

Abstract

A challenge facing immunization registries is developing measures of childhood immunization coverage that contain more information for setting policy than present vaccine series up-to-date (UTD) rates. This study combined milestone analysis with provider encounter data to determine when children either do not receive indicated immunizations during medical encounters or fail to visit providers. Milestone analysis measures immunization status at key times between birth and age 2, when recommended immunizations first become late. The immunization status of a large population of children in the Oregon ALERT immunization registry and in the Oregon Health Plan was tracked across milestone ages. Findings indicate that the majority of children went back and forth with regard to having complete age-appropriate immunizations over time. We also found that immunization UTD rates when used alone are biased towards relating non-UTD status to a lack of visits to providers, instead of to provider visits on which recommended immunizations are not given.

Sick-Visit Immunizations and Delayed Well-Baby Visits

“…7 Immunization records for study children were extracted from the ALERT Immunization Information System (IIS). IIS is a population-based data system capturing immunization doses administered by participating providers within a given area.…”

“…6 As an example, 1 recent US study found that 64.5% of undervaccination up to age 2 years was attributable to missed opportunities, whereas another recent study in India found that 79.6% of undervaccination up to age 6 years was related to missed opportunities. 7,8 One common type of missed opportunity is when a child presents sick when shots are due, with the added possibility that the sick visit will take the place of a routine or wellbaby visit. 9 This problem has long been recognized as among the more difficult barriers to address, and it can account for the majority of true missed opportunities at a practice.…”

Factors affecting childhood immunization in Lao People's Democratic Republic: A cross-sectional study from nationwide, population-based, multistage cluster sampling

“…Utilization of vaccination services is dependent on sociodemographic factors of the target population, as well as the number of health workers and availability of safe needles and syringes (5). Two studies show that children missed immunizations due to the provider's reluctance to vaccinate children while sick or when visiting health care centres for other purposes (9,28). This study did not focus on these provider risk factors.…”

Vaccinating My Way—Use of Alternative Vaccination Schedules in New York State

“…[6][7][8][9][10][11] Although several published alternative schedules exist, [12][13][14] studies have shown that most parents who admit not using the routine schedule opt for a more individualized alternative schedule approach often developed with friends or their pediatrician. 9,[15][16][17][18][19] Children who were under-vaccinated in a large group of managed care organizations were found to follow almost 1400 individualized vaccination patterns. 16 Despite this variability, 3 specific tactics associated with alternative schedules have emerged: delay of vaccines or particular doses (not because of unavailability or illness), selective refusal of specific vaccines, and a reduction in the number of vaccines given at each visit.…”