Association of pediatric COVID-19 vaccination and socioeconomic position: a nested case-control study from the Pedianet Veneto cohort

Background: The success of pediatric COVID-19 vaccination strongly depends on parents' willingness to vaccinate their children. To date, the role of socioeconomic position (SEP) in pediatric COVID-19 vaccination has not been thoroughly examined. Objective: To evaluate the association between COVID-19 vaccination and SEP in a large pediatric cohort. Methods: A case-control study design nested into a pediatric cohort of children born between 2007-2017 living in the Veneto Region and followed-up to at least January 1st, 2022, was adopted. Data on children was collected from the Pedianet database and linked with the regional COVID-19 registry. Each child vaccinated with at least one dose of any COVID-19 vaccine between July 1st, 2021 and March 31st, 2022, was matched by sex, year of birth, and family pediatrician to up to five unvaccinated children. Unvaccinated children with a positive swab within 180 days before the index date were excluded from the analyses. Children were georeferenced to determine their area deprivation index (ADI), a social and material deprivation measure calculated at the census block level and consisting of 5 socioeconomic items. The index was then categorized in quintiles based on the regional ADI level. The association between ADI quintiles and vaccination status was measured by conditioned logistic regression models to estimate odds ratios (ORs) and the corresponding 95% confidence intervals (95% CI). Quantile-g-computation-regression models were applied to develop a weighted combination of the individual items (WDI) to estimate how much each component influenced the likelihood of vaccination. All analyses were stratified by age at vaccination (5-11, 12-14 years). Results: The study population consisted of 6,475 vaccinated children, matched with 32,124 non-vaccinated children. Increasing area deprivation was associated with a lower probability of being vaccinated, with approximately a linear dose-response relationship. Children in the highest deprivation quintile were 36% less likely to receive a COVID-19 vaccine compared to children with the lowest deprivation (95%CI: 0.59-0.70). The results were similar in the two age groups, with a slightly stronger association in 5-11-year-old children. When assessing the effects of the WDI, a quintile increase was associated with a 17% decrease in the probability of being vaccinated (95%CI: 0.80-0.86). The conditions that influenced the probability of vaccination the most were living on rent, unemployment and single-parent families. Conclusions: This study has shown a significant reduction in the likelihood of receiving a COVID-19 vaccination among children living in areas characterized by a lower socioeconomic position. Findings were robust among multiple analyses and definitions of the deprivation index. These findings suggest that SEP plays an important role in vaccination coverage, emphasizing the need to promote targeted public health efforts to ensure global vaccine equity.