Abstract
BACKGROUND: Delayed vaccination is a well-studied and critical public health issue. However, limited studies have explored whether familial factors influence vaccination delay. This study aimed to determine whether family structure and comorbidities affect the refusal or delayed receipt of measles-rubella and varicella vaccines. METHODS: We gathered data on all children from birth to 13 months of age between 2006 and 2020 using vaccination records linked with the administrative healthcare claims data from a Japanese city. Multivariable logistic regression analyses were conducted to examine the association of refusal or delay in receiving the first-dose measles-rubella and varicella vaccines with the following factors: the child's sex; presence of parents, siblings, and grandparents; parental and grandparental comorbidities; chronic pediatric comorbidities in the child and siblings; and year of vaccination. RESULTS: We identified a total of 14,241 eligible children. Refusal or delayed receipt of the first-dose measles-rubella vaccine was associated with an adjusted odds ratio of 2.46 (95% confidence interval, 1.86-3.24) for maternal absence and 1.61 (1.44-1.80) for paternal absence. Similarly, the refusal or delay in receiving the first-dose varicella vaccine was associated with an adjusted odds ratio of 2.04 (95% confidence interval, 1.01-4.16) for maternal absence and 1.37 (1.12-1.69) for paternal absence. The presence of siblings and maternal comorbidities were significantly associated with vaccination delays. CONCLUSION: The absence of a parent, the presence of siblings, and maternal comorbidities were associated with the refusal or delay in receiving measles-rubella and varicella vaccines. Strategies for vaccine recommendation should therefore consider family structure and maternal comorbidities.