Multilevel social vulnerability and urban health in sub-Saharan Africa: Implications for adaptation across household, community, and city levels

As rapidly urbanizing settlements in sub-Saharan Africa face vulnerability to environmental hazards across spatial levels, understanding the multilevel structure of vulnerability is critical for advancing urban health and climate adaptation. This paper develops a conceptual framework to examine multilevel social vulnerability and its health impacts across cities in 28 African countries. By integrating household survey and spatial datasets, this study constructs vulnerability indicators at household, community, and city levels, employing principal component analysis to quantify social vulnerability at each level. Logistic regression models estimate the effects of vulnerabilities on child health outcomes, including under-five mortality, underweight, diarrhea, and acute respiratory infection (ARI). The analysis reveals substantial variations in vulnerabilities across the three spatial levels, each of which significantly impacts health. Household and community vulnerabilities are related to increased risks of underweight and diarrhea while household vulnerability is strongly associated with mortality. In large cities with populations over one million, the effects of city vulnerability become more pronounced across morbidity outcomes, particularly for severe ARI and diarrhea. These findings suggest that the health implications of vulnerabilities differ according to specific outcomes and urban settings, highlighting the importance of incorporating a multilevel perspective into urban health and adaptation planning.