COVID-19 Vaccination Uptake in Belgium : Sociodemographic and Socioeconomic Disparities

May 31, 2022 updated by: Sciensano

COVID-19 Vaccination Uptake in Belgium: Sociodemographic and Socioeconomic Disparities - A Retrospective Cohort Study

In January 2021, the vaccination campaign against coronavirus disease 2019 (COVID-19) started in Belgium. The vaccination campaign was conducted in several phases, with the first phase targeting priority groups starting in January 2021. The second phase began in June 2021 with the invitation of everyone aged 18 years and older before extending access to 12 years and older from summer 2021. Children aged 5-11 were also invited for vaccination from December 2021 onwards.

The presence of a social gradient in COVID-19 infections and subsequent outcomes has been clearly demonstrated. Individuals from lower socioeconomic groups, for example with lower income, lower education level or unemployed are more likely to be infected by the SARS-CoV-2 and to develop severe complications after the infection such as hospitalization, ICU admission or death. Certain sociodemographic characteristics such as male gender, older age, living in crowded households, or belonging to ethnic/racial minorities are also associated with a higher risk of COVID-19 infection and severe outcomes. In addition to disparities in infection, hospitalization and mortality, some studies have also documented a lower COVID-19 vaccination coverage among people from disadvantaged socioeconomic groups during COVID-19 pandemic.

Despite widespread vaccine promotion efforts and the fact that Belgium has the 7th highest full vaccine coverage in the European Union (89% of people over 18 years old had completed their primary course of vaccination on 08 April 2022), concerns regarding vaccine equity remain. Vaccine uptake depends on a range of factors, including the socio-cultural environment, pre-existing health needs and individual choice. Identifying differences in vaccination between population groups is crucial to assess the effectiveness of the vaccination strategy in Belgium and its relationship to the further spread of COVID-19.

The objective is to identify whether vaccination coverage has been equitable across Belgium and, if not, which groups of individuals are less likely to be covered by the COVID-19 vaccine, with respect to their sociodemographic (SD) and socioeconomic (SE) characteristics.

This study therefore aims to highlight SD and SE disparities in the uptake of the first dose of COVID-19 vaccine in Belgium among people of 18 years and over.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

  1. Study design and data sources

    In this retrospective cohort study, the investigators aimed to unravel SE and SD disparities in the uptake of the first COVID-19 vaccine dose using data from the LINK-VACC project. This project was launched by Sciensano, the institute legally responsible for the surveillance of infectious diseases in Belgium (Royal Decree of 21/03/2018), to perform the post-authorization surveillance of COVID-19 vaccines in Belgium.

    To that aim, selected variables from multiple existing national health and social sector registries were linked at an individual level using the unique Belgian social security number. The databases were linked within a pseudonymised environment hosted by Healthdata.be of Sciensano. For the present study, four databases were used :

    • Vaccinnet+, the Belgian vaccine registry, which contains information on all COVID-19 vaccine doses administrated in Belgium. It includes demographical data of the vaccinated person (sex, age, postal code of residence), as well as data on the vaccinator (type (person or organization) and postal code) and on the administrated vaccine (brand of the vaccine, lot number, date of administration, date of registration).
    • The COVID-19 Healthdata database containing data from COVID-19 laboratory tests performed in Belgium (data of sampling and test result).
    • The STATBEL database provided by the Belgian Statistical Institute which contains variables related to socioeconomic and sociodemographic characteristics.
    • The Common Base Registry for HealthCare Actor (CoBRHA) allowing the identification (by profession and specialty) of people who have been licensed to practice a healthcare profession in Belgium.

  2. Cohort definition

    The population of interest includes all individuals of 18 years and older tested for COVID-19 at least once in Belgium until the 31st of August 2021 (which is the date of linkage between STATBEL, Vaccinnet+ and the COVID-19 Healthdata database) for whom SD and SE information from STATBEL database was available.

    The cohort is built from Vaccinnet+ and the COVID-19 Healthdata database which includes all doses of vaccines administered and PCR and rapid antigenic tests performed in Belgium, respectively. As of 31 August 2021, 10 475 908 individuals had been tested and/or vaccinated at least once in Belgium according to Vaccinnet+ and the COVID-19 Healthdata database. On January 1, 2021, the official Belgian population included 11 521 238 inhabitants, demonstrating a high coverage of the total Belgian population by these two data sources (90.92%).

    The relevant SE and SD variables were then included after linking with STATBEL database based on the individual national identification number. The data source available from STATBEL contains SE and SD information for 10 309 300/10 475 908 individuals registered at least once either in Vaccinnet+ from 28 December 2020 to 31 August 2021 or in the COVID-19 Healthdata database before 31 August 2021, corresponding to a linkage rate of 98.41%. Information on the healthcare license available in CoBRHA were then added. After these linkages, people who were deregistered, migrated and deceased based on their status in the national registry were excluded. People whose age, region or gender were unknown were also excluded.

    In order to be able to compare vaccination rate according to each SE and SD indicators, the investigators included only individuals tested before 31 August 2021 since it is the date of linkage between Vaccinnet+, COVID-19 Healthdata database and STATBEL. Finally, individuals under 18 years of age were excluded as they were considered as a group in their own right in the vaccination strategy by being vaccinated the latest in a separate phase of the vaccination campaign.

    The final cohort for this study is therefore composed of 5 341 584 individuals of 18 years and over tested in Belgium until the 31st of August 2021.

  3. Outcome The outcome variable, provided by Vaccinnet+, is the uptake of the first dose of COVID-19 vaccine until the 31st of August 2021. The investigators considered that, at this date, all individuals over 18 years of age had received an invitation to be vaccinated with the first dose and had the opportunity to receive this dose of vaccine in Belgium.

Study Type

Observational

Enrollment (Actual)

5341584

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Belgium
      • Bruxelles, Belgium, 1000
        • Lisa Cavillot

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

All individuals of 18 years and over tested for COVID-19 at least once in Belgium before 31 August 2021

Description

Inclusion criteria :

  • Tested at least once in Belgium before 31 August 2021

Exclusion criteria :

  • people with a national registry status equivalent to deceased
  • people with a national registry status equivalent to migrated
  • people with a national registry status equivalent to deregistered
  • people with an unknown age
  • people with an unknown gender
  • people with an unknown region

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: Cohort
  • Time Perspectives: Retrospective

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
All individuals tested for COVID-19 in Belgium
All individuals of 18 years old and over tested for COVID-19 at least once in Belgium until the 31st of August 2021
Other: Education level
Educational level was classified using the International Standard Classification of Education (ISCED) : ISCED0 (less than primary education), ISCED1 (primary education), ISCED2 (lower secondary school), ISCED3 (upper secondary school), ISCED4 (post-secondary non tertiary education), ISCED5 (short-cycle tertiary education), ISCED6 (bachelor's or equivalent level), ISCED7 (master's or equivalent level), ISCED8 (doctoral or equivalent level). We merged these different categories into three main education level : low (ISCED0 to ISCED2), middle (ISCED3 to ISCED4) and high (ISCED5 to ISCED 8). This information is provided by STATBEL.
Other: Household net income
Income information is available as deciles of the net income of the whole household. This indicator is further categorized into low income (deciles 1 to 4), middle income (deciles 5 to 7), and high income (deciles 8 to 10). This information is provided by STATBEL.
Other: Gender
Male or female. This variable is obtained from the Belgian national registry.
Other: Migration background
Migration background is based on the first nationality and the parents' country of origin. This variable distinguishes between native-born individuals, second-generation migrants, first-generation European migrants, and first-generation non-European migrants. This information is provided by STATBEL.
Other: Household type
Household type provides a partial picture of the social environment and is distinguished between one person, couples, couples with children, single parents, other, collectivity (prison, nursing homes, religious community, etc.). This information is provided by STATBEL.
Other: Health literacy
Having a health care degree is used as a proxy for health literacy and is provided by CoBRHA. The scientific and medical background can lead to more preventive and responsible behaviors towards infectious diseases. Moreover, being a health professional can lead to the need to protect patients and themselves against infections, without necessarily having very advanced knowledge of infectious diseases and vaccines.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of participants who received the first dose of COVID-19 vaccine
Time Frame: 28 December 2020 - 31 August 2021
Uptake of the first COVID-19 vaccine dose until the 31st of August 2021 in Belgium
28 December 2020 - 31 August 2021

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sciensano

Investigators

  • Principal Investigator: Lucy LC Catteau, PhD, Sciensano

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

December 28, 2020

Primary Completion (Actual)

August 31, 2021

Study Completion (Actual)

August 31, 2021

Study Registration Dates

First Submitted

May 12, 2022

First Submitted That Met QC Criteria

May 12, 2022

First Posted (Actual)

May 13, 2022

Study Record Updates

Last Update Posted (Actual)

June 3, 2022

Last Update Submitted That Met QC Criteria

May 31, 2022

Last Verified

March 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • B.U.N. 1432020000371

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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