Socioeconomic Inequalities in COVID-19 Vaccination and Infection Among Adults Living in Urban Areas of Catalonia, Spain: A Population-based Cohort Study

Background: Evidence on the impact of the COVID-19 vaccine rollout on inequalities in COVID-19 infections is lacking.

Objectives: To analyse the associations between deprivation and COVID-19 vaccination rollout, as well as COVID-19 infections and hospitalisations before and after vaccine rollout.

Methods: Population-based cohort study from 1 September 2020 to 30 June 2021 using primary care records from Catalonia, Spain. We included 2,297,146 adults eligible for vaccination (aged ≥40 years) living in urban areas without missing data on deprivation. Deprivation was assessed using quintiles of socioeconomic deprivation index at census tract areas. We described COVID-19 vaccination coverages (%) and incidence rates (IR) per 100,000 person-years of COVID-19 infections and hospitalisations over time by deprivation quintile. We estimated Odds Ratio (OR) of non-vaccination (at study end), and Hazards Ratios (HR) of COVID-19 infection and hospitalisation (3 months before and 1 to 6 months after vaccine rollout) by deprivation. Models were relative to the least deprived quintile (Q1), and adjusted for age, sex and nationality. Results were stratified by age group: ≥65 and 40-64 years.

Results: Six months after vaccine rollout, vaccination coverage was high, but differed by deprivation quintile (Q1: 84.6%, Q5: 76.7%). When compared to Q1 areas, OR of non-vaccination increased with deprivation among working-age individuals (40-64 years; OR [95%CI]: 1.01 [1.00;1.02], 1.08 [1.07;1.10], 1.11 [1.10;1.13], 1.33 [1.31;1.35] for Q2, Q3, Q4, and Q5 areas, respectively); but not among retirement-age individuals (≥65 years). Before vaccine rollout, a pattern of increased rates of infection and hospitalisation with deprivation was seen among both age groups. One to 6 months after vaccine rollout, inequalities in COVID-19 infection decreased substantially among all individuals, whereas inequalities in hospitalisations decreased only among retirement-age individuals. For example, among retirement-age individuals, HR for Q5 areas were 1.54 [1.46;1.61] and 1.23 [1.16;1.31] for infections before and after vaccine rollout, and 1.99 [1.80;2.19] and 1.52 [1.36;1.71] for hospitalisations before and after vaccine rollout, respectively.

Conclusions: Despite inequalities in vaccination coverage, inequalities in COVID-19 infection and hospitalisation decreased six months after vaccine rollout in Catalonia. Our findings support COVID-19 massive immunisation programs as a strategy to reduce COVID-19-related inequalities and underline the importance of increasing vaccination across all population subgroups.