Syndemics

Syndemics is a framework in public health for examining how two or more health conditions co-occur in a population and interact in ways that worsen overall health outcomes, particularly in settings marked by social disadvantage. The concept foregrounds not only the diseases themselves but the social, economic, and environmental contexts that shape risk, vulnerability, and resilience.

The term was introduced by Merrill Singer in the 1990s to describe the synergistic clustering of epidemics within marginalized communities. A classic example is the SAVA syndemic—Substance abuse, Violence, and AIDS—observed among urban populations in the United States, illustrating how social conditions and disease dynamics reinforce one another.

Core ideas of syndemics include the clustering of conditions, biologic or behavioral interactions that magnify harm, and structural drivers such as poverty, discrimination, lack of access to care, and inadequate social support. Syndemics differ from simple comorbidity or coinfection by emphasizing the interactions among diseases and the material and social environments that sustain them.

Examples beyond SAVA include tuberculosis and HIV in impoverished settings, malnutrition and infectious diseases in sub-Saharan Africa, and the way COVID-19 outcomes have been shaped by housing instability, unemployment, and racial and ethnic inequities. In some contexts, obesity, diabetes, and mental health problems form interacting epidemics influenced by social determinants.

Implications for policy and research focus on integrated, multisectoral interventions that address both biomedical needs and structural determinants, along with analytic approaches that capture disease interactions and their social contexts.