Severe Childhood Obesity, Immune Dysfunction, and Elevated Infection Risk: A Critical Review

Abstract

Severe childhood obesity has become one of the more pressing public health concerns of recent decades, affecting millions of children in both high-income and low- and middle-income settings. Its metabolic and cardiovascular consequences are well documented, but a growing body of evidence points to a further, less appreciated dimension: severe obesity disrupts immune function in ways that leave affected children more vulnerable to infectious disease. This review examines that evidence, focusing on how severe paediatric obesity alters innate and adaptive immunity, sustains chronic low-grade inflammation, disturbs adipokine signalling, and interacts with obesity-related comorbidities to compound infection risk. It also considers how gut microbiome disruption, blunted vaccine responses, and impaired respiratory defences combine to worsen outcomes once infection takes hold. Findings from the COVID-19 pandemic and the influenza literature are used to illustrate how severe obesity behaves as an independent risk factor for serious paediatric infectious illness, while nutritional considerations — particularly the micronutrient deficiencies that often accompany obesity — are discussed in relation to immune competence. The review further considers how poverty, food insecurity, and unequal healthcare access intersect with the biological picture, concentrating risk in already disadvantaged populations. Gaps in the literature are identified, and priorities for future research are proposed. Taken together, the evidence points to a complex, mutually reinforcing relationship between adiposity and immune dysfunction that calls for a more integrated clinical and public health response than is currently typical.