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

"Understanding the network ties that classmates establish and maintain after school is of interest to implement effective vaccination strategies at organizational, regional, and national levels."

Given the mutual dependency between social interactions and health behaviours, friendships may be an important element for adolescents' health. Social networks represent "pipes" through which information and opinions circulate and spread out in the social circle surrounding individuals, influencing their choices about healthcare interventions, including vaccines. Meanwhile, a movement against vaccination is growing through traditional media channels, social media platforms, and online communities, leading to distrust and vaccine hesitancy. In this context, this study explores the relationship between Italian pupils' positive responsiveness to vaccination and their friendship networks maintained during school hours (school network) and outside school hours (after-school network).

In Italy, routine immunisation programmes, including poliovirus and diphtheria-tetanus (DPT) have been mandatory since the early 1960s. The Hepatitis B vaccine was added in 1991. Other vaccinations, even if not mandatory, are free of charge, are strongly recommended by the Italian Ministry of Health, and are included in health benefit packages. Public facilities are in charge of providing vaccination to children, and paediatricians and general practitioners (GPs) run counselling activities for their communities and families about vaccines. Moreover, a prominent role in health promotion activity is played by schools.

The study is part of the Italian research project "VacciniAmo le Scuole", which aimed at encouraging the promotion of vaccination and primary prevention across the Italian educational system. As part of the larger project, a 90-minute training programme about vaccination was carried out in all 4 classrooms of a secondary school located in central Italy. Public health physicians provided background information about vaccines, and a role-playing activity allowed participants to experience practical situations about immunisation. The training gave researchers the opportunity to administer a structured paper questionnaire to 49 attending students to collect data on individual students' demographics, knowledge, and attitudes about vaccinations, as well as their social networks (e.g., the classmates with whom they talk the most and usually spend time with during school hours, as well as after school hours).

In order to investigate the social processes underlying the configuration of the 2 friendship networks observed (during and after school), 3 different social mechanisms were taken into consideration: (i) Given the positive emotions generally involved in a friendship, the researchers considered the reciprocity of pupils' relational ties. (ii) They considered the networks' closure, which refers to the natural tendency of individuals to triangulate in their networks and, eventually, to connect and cooperate within small groups. (iii) The preferential attachment indicates the likelihood of actors to link to others depending on their level of popularity.

The researchers applied a logistic regression quadratic assignment procedure (LR-QAP) by regressing students' positive responsive behaviour similarity as a dependent variable. LRQAP findings indicate that students' vaccination behaviour 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 behaviours through social relationships maintained after school hours rather than through those established during the school day. Moreover, the researchers found that vaccination behaviours are more similar for those students having the same ethnicity and for those belonging to the same class.

Although schools are recognised as promising social contexts for health promotion activities, these results seem to suggest that more effective interventions are needed to foster the interaction between schools and the surrounding environment and to translate planning objectives into genuine benefits for the intended population: adolescents. In Italy, say the researchers, "it is necessary to take into account the numerous challenges school managers have had to face in the recent past and present, such as job insecurity of teachers, lack of financial resources, and infrastructure inadequacy. Some critical points have to be addressed to effectively manage prevention programs, which should regard capacity building activities for project management, commitment, and leadership, as well as the availability of human, financial, material, and temporal resources..."

According to the researchers, the use of social network analysis may be of interest to those who are interested in exploring the mechanisms underlying the social structures of any community and setting. Furthermore, the results may be helpful for policymakers and school managers seeking to develop targeted vaccination campaigns using social network data. Such health promotion campaigns could be delivered in institutional or recreational places, taking into account social ties.

Reflecting on their attempt to incorporate social network effects into the study of vaccine hesitancy and its determinants, the researchers conclude that, if replicated on a broader scale, "this study could better inform policymakers to promote strategies aimed at tackling vaccination hesitancy."