Adherence to recommended immunization schedule during adolescence: findings of a cross-sectional study in the Southern part of Italy.

backgroundAdolescence is a pivotal life stage during which individuals develop health-related attitudes and behaviours that frequently persist into adulthood, making it a crucial period for shaping long-term engagement with preventive care. Despite Italy's national recommendations for adolescent vaccines (HPV, MenACWY, and the dTap-IPV booster), coverage gaps persist. By analyzing the self-reported vaccination history of university students, this study aims to assess adolescent vaccine adherence, willingness to vaccinate and their predictors to better inform targeted public health interventions.

methodsA cross-sectional survey was conducted among university students (aged 18-29 years). An online, anonymous, self-administered questionnaire was developed to gather data on socio-demographic characteristics, past adherence to vaccinations offered during adolescence (i.e., HPV and MenACWY vaccines and the dTap-IPV booster), willingness to get vaccinated, factors influencing vaccination decision making, and sources of information on vaccinations.

resultsAmong the 527 enrolled participants, 29% reported having received the MenACWY vaccine during adolescence, with the lack of healthcare worker (HCW) recommendation cited as the leading barrier (59.4%). HPV vaccine uptake was the strongest predictor of being vaccinated against MenACWY vaccination. A majority of the students (68.3%) reported receiving the HPV vaccine during adolescence, primarily to prevent HPV-related cancers (55.8%). Female sex, younger age, and higher parental education were positively associated with the HPV vaccine uptake. Additionally, 89.4% received the dTap-IPV booster, and this uptake was positively associated with both HPV and MenACWY vaccination. Notably, one-third (31.1%) reported that an HCW had discouraged vaccination, and even though nearly all (99.4%) cited HCWs as their primary source of information on vaccination.

conclusionsA persistent gap in adolescent vaccination adherence remains, particularly for MenACWY and HPV, driven by unbalanced risk perceptions and frequent missed clinical opportunities by HCWs. Conversely, vaccine mandates ensured high dTap-IPV coverage. The strong correlation across vaccine types highlights the potential of "clustered" immunization behaviors. To bridge these coverage gaps, interventions must strengthen HCW counseling, utilize low-friction delivery models like school-based clinics, and deploy dual-targeted strategies that reframe vaccination as a shared social responsibility.