Social backgrounds and childhood respiratory infections
Children from lower socio-economic backgrounds are more susceptible to contracting respiratory infections and are also more likely to suffer long-term complications. Yet despite growing awareness, there is little known about the exact mechanisms linking social disadvantage to childhood respiratory disease. Respiratory infections arise from multiple overlapping early-life factors, such as housing and environmental conditions, which often cluster within socio-economic groups and interact in complex ways. Previous research has not examined these mechanisms systematically across populations. A further challenge exists in the heterogeneity of inequality patterns across countries and different stages of childhood. “Because of this complexity, the underlying pathways remain insufficiently understood,” says Demetris Avraam(opens in new window), postdoc researcher at the University of Copenhagen(opens in new window). Through the ESICRI project, which was supported by the Marie Skłodowska-Curie Actions(opens in new window) programme, Avraam sought further insights into the underlying mechanisms behind the link, through a broad investigation and data analysis on over 200 000 children across 16 European birth cohorts. His aim was to explore the social, geographic and cultural pathways that connect early-life risk factors with these infections, to better understand their burden in children across Europe.
Pan-European analysis of childhood respiratory tract infections
The project work began with descriptive analyses to characterise the prevalence of upper and lower respiratory tract infections across childhood, overall and by maternal education, the main indicator of children’s socio-economic background. Avraam then applied statistical modelling to quantify socio-economic inequalities at different ages. These models produced two inequality measures: absolute (difference in infection prevalence between the lowest and highest socio-economic groups) and relative (prevalence ratio between the lowest and highest socio-economic groups). In parallel, Avraam developed the ‘dsMediation package’, a statistical tool that allows for causal mediation analysis while preserving participant data privacy. This allowed ESICRI to establish the analytical framework for examining early‑life environmental, behavioural, psychosocial and perinatal factors as potential mediators while supporting Europe’s digital and data‑protection priorities.
Unpicking connection between infection rates and inequality gradients
The project generated several key findings, including that childhood respiratory tract infections follow clear age‑related patterns, with upper respiratory tract infections peaking around ages one and three and lower respiratory tract infections around ages two and four. “These consistent developmental patterns across countries provide a robust evidence base for early‑life prevention strategies,” notes Avraam. Another key insight from the project was a marked variation in infection rates and inequality gradients across cohorts and countries. While inequalities appeared stronger in some countries, they were weaker or reversed in others, suggesting context and environmental conditions play a major part in infection risk.
Feeding into European policy for preventative action
The findings have clear practical policy relevance, says Avraam. “The clear age‑specific peaks highlight early‑childhood settings, particularly day care and preschool, as key environments for preventive action,” he adds. The cross‑country comparisons suggest social and environmental conditions can be modified to reduce infection risk, particularly policies targeting childcare environments, housing quality, parental support and early‑life health behaviours. “The results highlight early childhood – particularly day care and preschool environments – as critical points for preventive action,” remarks Avraam. “This evidence can support policies that strengthen infection‑control practices, improve ventilation and hygiene standards, and promote healthier early‑life environments.” Avraam will continue the work, to uncover the complex pathways linking socio-economic disadvantage to childhood respiratory infections. He also plans to work with cohort partners to explore cross-country contextual factors and extend this research to other child health outcomes, such as mental health and obesity – with the ultimate aim of generating evidence to help reduce child health inequalities across Europe.
