Determinants of COVID 19 Vaccine Intention: A Cross Sectional Study with Decision Tree Analysis

Background

In the post-pandemic phase, sustaining uptake of COVID‑19 boosters remains a public health priority. However, limited evidence exists on how socioeconomic and attitudinal factors interact to shape the hesitancy profiles. This study assessed the intention to receive an annual COVID‑19 booster among Italian adults.

Methods

A survey was conducted among Italian adults aged ≥ 18. We defined vaccine hesitancy (VH) as an annual booster intention score<25 on a 0–100 scale. Multivariable logistic regression was used to identify factors associated with VH. A classification and regression tree (CART) analysis was performed using the Gini index and pruned according to the one-standard-error rule with cross-validation to identify population subgroups with distinct hesitancy profiles.

Results

A total of 1,821 adults (mean age 54 years) were enrolled. VH was significantly associated with economic hardship and a tendency to avoid healthcare services, whereas higher perceived quality of the NHS, favorable attitudes toward vaccination and SARS-CoV-2 risk, and being a student or retiree were protective. CART analysis identified agreement with COVID-19 vaccine mandates as the first discriminator of hesitancy profiles: individuals with low agreement showed the highest prevalence of VH (86.4%). Among those with higher agreement, perceived vaccine safety further differentiated risk, with markedly lower VH (23.8%) among participants reporting high safety perceptions than among those with lower perceived safety (55.2%).

Conclusions

COVID-19 booster hesitancy is driven by the interplay of socioeconomic conditions, healthcare engagement, and trust-related attitudes. Agreement with mandates and perceived vaccine safety define distinct hesitancy profiles, supporting the need for targeted communication and policy strategies. Decision tree modeling offers a practical approach to segment populations and tailor interventions in post-pandemic vaccination programs.

Key messages

• Key socioeconomic and attitudinal factors influence COVID 19 booster hesitancy in Italian adults.

• Mandate agreement and perceived vaccine safety strongly shape hesitancy profiles.