A0858
Title: Unravelling timing and determinants of childhood vaccination: The Italian case
Authors: Chiara Chiavenna - Bocconi University (Italy) [presenting]
Filippo Trentini - Bocconi University (Italy)
Catia Rossana Borriello - Lombardy Region (Italy)
Michele Ercolanoni - ARIA SPA (Italy)
Giuseppe Preziosi - ARIA SPA (Italy)
Pierluca Colacioppo - ARIA SPA (Italy)
Danilo Cereda - Lombardy region (Italy)
A. Melegaro - Bocconi University (Italy)
Abstract: Vaccination coverage (VC) is an important proxy of a population's level of protection against a specific pathogen. When VC is below a given threshold, public health officers implement policies encouraging uptake. The population subgroups that an optimal intervention should target are identified. Routine childhood vaccination records of 860,677 Lombardy residents born between 2006 and 2019 were extracted. Sequence analysis was used to summarize their vaccination behaviour: vaccination timings are expressed as life trajectories, with individual states indicating the number of doses received at each time unit. A distance matrix quantifying dissimilarity between sequences was used to cluster individuals; finally, a multivariate regression model was trained to predict cluster classification based on parental age, education, employment, nationality, and COVID-19 vaccination. For the hexavalent vaccine, four clusters of individuals were identified, labelled as vaccinated on time (90.19\%), delayed vaccination (6.69\%), interrupted the cycle (1.72\%), and did not vaccinate (1.39\%). For measles, higher proportions of children interrupted the cycle (4.15\%) or did not vaccinate (2.35\%). A higher probability of delaying or refusing vaccination was estimated for children with mothers unvaccinated against COVID-19. Children with at least one foreign parent or unemployed fathers were also at higher risk of non-compliance.
