The Impact of School and After-School Friendship Networks on Adolescent Vaccination Behavior.

Psychological and social characteristics of individuals are important determinants of their health choices and behaviors. Social networks represent "pipes" through which information and opinions circulate and spread out in the social circle surrounding individuals, influencing their propensity toward important health care interventions. This paper aims to explore the relationship between students' vaccination health choices and their social networks. We administered a questionnaire to students to collect data on individual students' demographics, knowledge, and attitudes about vaccinations, as well as their social networks. Forty-nine pupils belonging to 4 classrooms in an Italian secondary school were enrolled in the study. We applied a logistic regression quadratic assignment procedure (LR-QAP) by regressing students' positive responsive behavior similarity as a dependent variable. LRQAP findings indicate that students' vaccination behavior similarity is significantly associated with after-school social ties and related social mechanisms, suggesting that pupils are more likely to share information and knowledge about health behaviors through social relationships maintained after school hours rather than through those established during the school day. Moreover, we found that vaccination behaviors are more similar for those students having the same ethnicity as well as for those belonging to the same class. Our findings may help policymakers in implementing effective vaccination strategies.