# Differences in routine childhood immunization uptake between single and multiple healthcare facility use: the Kochi Adjunct Study of Japan Environment and Children’s Study

## TL;DR

Children who received all their vaccinations at a single healthcare facility had better immunization completion rates than those who used multiple facilities.

## Contribution

This study identifies a link between consistent healthcare facility use and higher childhood immunization completion rates in Japan.

## Key findings

- 76.6% of children completed routine childhood immunizations by age eight.
- Single facility use was associated with higher immunization completion compared to multiple facility use.
- Multiple facility use throughout the vaccination period had the strongest association with incomplete immunization.

## Abstract

The efficacy of routine childhood immunization depends on timely vaccine uptake and facility use patterns. This study examined the association between pediatric vaccination facility use patterns and routine childhood immunization uptake among children up to age eight years.

As part of the Kochi Adjunct Study of the Japan Environment and Children’s Study (JECS), we analyzed data from 1,644 participants whose Maternal and Child Health Handbook photographs were collected in the eighth year of the cohort study. Maternal and Child Health Handbook records determined immunization completion. Participants were categorized into four groups based on pediatric vaccination facility use patterns: single facility use throughout, multiple facility use during the first period, multiple facility use during the second period, and multiple facility use throughout both periods. Maternal and child characteristics were collected via paper-based questionnaires. Associations between facility use patterns, sociodemographic factors, and immunization completion were analyzed using chi-square tests and logistic regression.

Overall, routine childhood immunization completion was observed in 1,259 (76.6%) participants. Chi-square tests indicated that marital status, educational level, lower parity, never smoking, not attending nursery, and breastfeeding practice for infants aged four months old were significantly associated with routine childhood immunization completion. Single facility use throughout the immunization period was observed in 1,011 (61.5%) participants. Multiple facility use (38.5%) was associated with higher odds of routine childhood immunization incompletion than single facility use. This association was the strongest for those who used multiple facilities throughout the vaccination period (adjusted odds ratio, 1.90; 95% confidence interval, 1.24–2.91).

Single pediatric facility use was associated with higher routine immunization uptake. Our findings suggest that encouraging the use of one medical institution for a child’s vaccinations may be a useful approach to consider when addressing vaccination coverage challenges.

The online version contains supplementary material available at https://doi.org/10.1265/ehpm.25-00028.