Syndemic health inequalities during the COVID-19 pandemic: an immuno-epidemiological approach to tackle Unequal vulnerability and Unequal susceptibility in the general population (SHIELD-U²)
During the COVID-19 pandemic, people with multiple health conditions were disproportionately affected. Multimorbidity and immune system sensitivity are linked to both infection risk and recovery. It is still unclear whether, and how, these factors contribute to mortality after COVID-19. This study examined the impact of COVID-19 on mortality in individuals with multimorbidity, focusing on the potential role of antibody glycosylation.
Goal
- Determine the role of multimorbidity in relation to mortality during and after the COVID-19 pandemic.
- Assess the role of antibody glycosylation in protection against COVID-19 in individuals with multimorbidity.
Approach
This study included participants from the Rotterdam Study, a population-based study in the Ommoord district of Rotterdam, who have been followed since the start of the COVID-19 pandemic in February 2020. They assessed how many of these participants had multimorbidity. COVID-19 cases were identified through medical records, PCR test data from the RIVM, and questionnaires from the Rotterdam Study. Finally, they measured antibody glycosylation (IgG glycosylation) in these participants, in collaboration with their partner at the Leiden University Medical Center (LUMC).
Collaboration partners
The project collaborated with various partners, including patient representatives from organisations such as the Lung Foundation Netherlands and PostCOVID Netherlands, as well as healthcare professionals. For example, they worked with the Dutch Association of Internists (NIV) to organise a symposium on multimorbidity. They also engaged directly with study participants through panel meetings and a webinar. These cross-disciplinary collaborations helped the researchers, focused on the project’s goals and how to achieve the greatest impact for clinical practice.
Results
The study followed 1,823 people with multimorbidity; 604 died. Among those who had COVID-19, the risk of death was 26% higher than in those without COVID-19. They then analysed IgG glycosylation in 4,337 individuals, of whom 26.6% eventually contracted COVID-19. Specific glycosylation traits (e.g., sialylation and galactosylation) were linked to an 11–13% higher COVID-19 risk per unit increase. Multimorbidity further increased this risk by 36-45%. These findings highlight the need for targeted prevention and continued research. COVID-19 still poses a serious health risk for people with multimorbidity and has not disappeared.
Follow-up activities
The data processing in this project allows the researchers to seamlessly connect with the PostCOVID19 network, thanks to detailed information on COVID-19 and various diseases. This rich dataset enhances the existing postCOVID-19 infrastructure in the Netherlands. Within this collaboration, they will develop further research projects. They hope to continue exploring the syndemic between infectious diseases and multimorbidity, either within or beyond existing ZonMw programs.