Family Characteristics Associated with Likelihood of Varicella Vaccination.

CONTEXT The introduction of the varicella vaccine as a routine pediatric immunization in the US, in 1995, provided an opportunity to assess factors associated with uptake of new vaccines in the member population of the Kaiser Permanente Northwest (KPNW) Health Plan. OBJECTIVE Identify factors associated with varicella vaccination in the KPNW population in the first five years after varicella vaccine was introduced. DESIGN A retrospective cohort of children under age 13 years between June 1995 and December 1999, without a history of varicella disease was identified using KPNW automated data. Membership records were linked to vaccine databases. Cox regression was used to estimate likelihood of varicella vaccination during the study period in relation to age, sex, primary clinician's specialty, and Medicaid eligibility. For a subset whose parents answered a behavioral health survey, additional demographic and behavioral characteristics were evaluated. MAIN OUTCOME MEASURE Varicella vaccination. RESULTS We identified 88,646 children under age 13 years without a history of varicella; 22% were vaccinated during the study period. Varicella vaccination was more likely among children who were born after 1995, were not Medicaid recipients, or had pediatricians as primary clinicians. In the survey-linked cohort, positively associated family characteristics included smaller family size; higher socioeconomic status; and parents who were older, were college graduates, reported excellent health, and received influenza vaccination. CONCLUSION Understanding predictors of early varicella vaccine-era vaccine acceptance may help in planning for introduction of new vaccines to routine schedules.