The impact of socioeconomic vulnerability on the incidence of COVID-19 in school students

Inequalities have been observed in the spread of COVID-19 due to higher incidence rates in environments with greater socioeconomic deprivation. The objective of this study was to analyse the relationship between socioeconomic level and the incidence of COVID-19 in students of schools in the city of Barcelona, in different epidemic waves. Cross-sectional ecological study on compulsory education students (N = 176,390). Unit of analysis: the 780 schools in the city. Study period: second (autumn 2020), third (winter 2020-21) and sixth epidemic waves (winter 2021-22). Dependent variable: Cumulative Incidence (CI) of COVID-19 among school students. Independent variables: complexity and ownership of the school, indexes in quartiles (being Q4 the most disadvantaged) of vulnerable students of the school and the Available Family Income (AFI) of the neighbourhood of the school. Stratified by sex and educational stage (Primary/Secondary). A bivariate and multivariate analysis was performed using Poisson regression to calculate crude Relative Risks and adjusted (aRR). As an impact measure, the Population Attributable Risk was calculated. In the second wave, 41% of the CI in primary boys was attributed to the vulnerability of the school (Q4: aRR=1.96 [1.10-3.50]), and 36% to a lower AFI in the neighbourhood of the school in secondary boys (Q4: aRR=3.18 [1.25-8.13]). Instead, in the sixth wave, taking Q4 as a reference, 35% of the CI in primary girls was attributed to lower vulnerability indices of the school (Q1: aRR=1.82 [1.52-2.20]), and 38% higher AFI from the neighbourhood of the school in secondary girls (Q1: aRR=1.99 [1.33-2.98]). In the third wave, the results are mixed and less significant in the models. The results obtained show that there was an inversion of the impact of social inequalities in the CI of COVID-19 in the second wave compared to the sixth. This reflects the need to delve into the contextual factors that favour the spread of communicable diseases. KEY MESSAGES: • The socioeconomic vulnerability of school students has been associated with a higher Cumulative Incidence of COVID-19 in the second wave, but this pattern has been reversed in the sixth wave. • Between 18 and 41% - depending on gender, educational level and epidemic wave- of the Cumulative Incidence of COVID-19 in Barcelona schools can be attributed to factors of socioeconomic deprivation.