Socioeconomic Inequalities in COVID-19 Vaccination and Infection in Adults, Catalonia, Spain

Abstract

Evidence on the impact of the COVID-19 vaccine rollout on socioeconomic COVID-19-related inequalities is scarce. We analyzed associations between socioeconomic deprivation index (SDI) and COVID-19 vaccination, infection, and hospitalization before and after vaccine rollout in Catalonia, Spain. We conducted a population-based cohort study during September 2020-June 2021 that comprised 2,297,146 adults >40 years of age. We estimated odds ratio of nonvaccination and hazard ratios (HRs) of infection and hospitalization by SDI quintile relative to the least deprived quintile, Q1. Six months after rollout, vaccination coverage differed by SDI quintile in working-age (40-64 years) persons: 81% for Q1, 71% for Q5. Before rollout, we found a pattern of increased HR of infection and hospitalization with deprivation among working-age and retirement-age (>65 years) persons. After rollout, infection inequalities decreased in both age groups, whereas hospitalization inequalities decreased among retirement-age persons. Our findings suggest that mass vaccination reduced socioeconomic COVID-19-related inequalities.

Keywords: COVID-19; COVID-19 vaccines; SARS-CoV-2; Spain; coronavirus disease; electronic health records; health inequities; respiratory infections; severe acute respiratory syndrome coronavirus 2; social class; socioeconomic factors; viruses; zoonoses.

Figure 1

Flowchart showing the inclusion and exclusion criteria for study population in analysis of socioeconomic inequalities in COVID-19 vaccination and infection in adults, Catalonia, Spain. SDI, Socioeconomic Deprivation Index; SIDIAP, Information System for Research in Primary Care.

Figure 2

Vaccination coverage and incidence rates of COVID-19 infection, hospitalization, and death over time by SDI quintile and age group in study of socioeconomic inequalities in COVID-19 vaccination and infection, Catalonia, Spain, 2020–2021. Only persons with complete follow-up were included to estimate vaccination coverages. Gray area shows the first month after the start of vaccine rollout (December 27, 2020). Q1 represents the least deprived quintile, Q5 the most deprived. A) Vaccination coverage by age group, shown as percentage of population. B) COVID-19 infections by age group, shown as incidence rate per 100,000 person-years. C) COVID-19 hospitalizations, shown as incidence rate per 100,000 person-years. COVID-19–related deaths, shown as incidence rate per 100,000 person-years. Q, quintile; SDI, Socioeconomic Deprivation Index.

Figure 3

Odds ratios of nonvaccination 6 months after the start of COVID-19 vaccine rollout by Socioeconomic Deprivation Index quintile, stratified by age group, in study of socioeconomic inequalities in COVID-19 vaccination and infection, Catalonia, Spain, 2020–2021. A) OR for retirement-age persons >65 years of age. B) OR for working-age persons 40–64 years of age. Q1, the referent quintile, represents the least deprived areas; Q5, the most deprived. Persons with complete follow-up (n = 2,258,866) after vaccination were included. Models are adjusted for age, sex, and nationality. Dots indicate OR; bars, 95% CI. OR, odds ratio; Q, quintile.

Figure 4

Fully adjusted hazard ratios of COVID-19 infection (A), hospitalization (B), and death (C) before and after vaccine rollout, by Socioeconomic Deprivation Index quintile and stratified by age group, in study of socioeconomic inequalities in COVID-19 vaccination and infection, Catalonia, Spain, 2020–2021. Q1, the referent quintile, represents the least deprived areas; Q5, the most deprived. Vaccine rollout started on December 27, 2020. Models before vaccine rollout are from September 1–December 26, 2020. Models after vaccine rollout are from January 27–June 30, 2021. All models are adjusted for age, sex, and nationality. Models in which the number of events for >1 deprivation area was <5 were not estimated. Dots indicate OR; bars, 95% CI. Q, quintile. HR, hazard ratio.