Immunization milestones: a more comprehensive picture of age-appropriate vaccination

Area of Science:

• Public Health
• Immunization Science
• Health Informatics

Background:

• Current childhood immunization coverage metrics, like vaccine series up-to-date (UTD) rates, offer limited insights for policy decisions.
• Immunization registries require more informative measures to understand coverage gaps effectively.

Purpose of the Study:

• To develop and apply a novel method combining milestone analysis with provider encounter data.
• To identify specific reasons for incomplete childhood immunizations: missed provider visits versus missed vaccines during visits.

Main Methods:

• Utilized milestone analysis to assess immunization status at critical ages between birth and two years.
• Tracked immunization status of a large cohort of children using the Oregon ALERT immunization registry and Oregon Health Plan data.
• Analyzed provider encounter data in conjunction with immunization records.

Main Results:

• The majority of children exhibited fluctuating immunization status over time, moving between complete and incomplete coverage.
• Standard UTD rates alone inaccurately attribute non-coverage primarily to missed provider visits.
• Analysis revealed a significant proportion of children do not receive recommended immunizations even when visiting providers.

Conclusions:

• Milestone analysis provides a more nuanced understanding of childhood immunization coverage dynamics.
• Policy-relevant insights can be gained by differentiating between missed visits and missed immunizations during encounters.
• Rethinking coverage metrics is crucial for improving public health interventions and vaccination strategies.