Risk score for non-vaccination of voluntary vaccines: The Japan Environment and Children's Study.

Background: In Japan, as several important vaccines are still categorized as voluntary vaccines that require out-of-pocket payment, the vaccination coverage of voluntary vaccines is lower than that of routine vaccines. Thus, higher voluntary vaccination rates are desired. Herein, we used nationwide birth cohort data to create a voluntary vaccine risk score to identify high-risk individuals who were not vaccinated with voluntary vaccines.

Methods: The data from 74,733; 73,571; and 74,360 infants were analyzed for rotavirus, mumps virus, and influenza virus vaccinations, respectively. The risk score for non-vaccination of voluntary vaccines was created from the regression coefficients of the logistic regression models.

Results: The items included for the score resulted from the analysis were the mother's drug allergy history, mother's depression history, mother's educational background, father's educational background, household income, maternal smoking during pregnancy, paternal smoking during pregnancy, fertility treatment, number of siblings, maternal drinking at 1 month of age, maternal age, and maternal nationality. The mother's drug allergy history, mother's depression history, fertility treatment, maternal drinking at 1 month of age, and maternal nationality were factors not previously reported and associated with taking voluntary vaccine. The receiver operating characteristic curve of the risk score for non-vaccination of voluntary vaccines suggested that a score ≥16 predicted non-vaccinated infants for rotavirus, mumps virus, and influenza virus vaccines with 78.6%, 75.0%, and 74.5% sensitivity and 44.2%, 43.2%, and 37.1% specificity, respectively.

Conclusions: We developed a risk score for non-vaccination of voluntary vaccines consisting of 10 domains with high sensitivity but low specificity.