Aging and Infection: Impact of Immunosenescence and Inflammaging in Respiratory Viral Infections

A strong yet appropriate immune response is essential for the timely control and clearing of respiratory viral infections. However, as physical condition declines with age, so does immune function. Immunosenescence is an age-related immune dysfunction marked by dysregulation of innate immune pathways, thymic involution, decreased T and B cell numbers and function, altered metabolism, and epigenetic changes. Additionally, older individuals often develop inflammaging, a condition characterized by elevated levels of proinflammatory markers. This deterioration of immune function in older adults significantly impairs viral control and increases disease severity. Studies consistently show a progressive rise in hospitalization and mortality rates with age. This review discusses the complex relationship between aging, immunosenescence, and inflammaging during respiratory viral infections, as well as the underlying mechanisms that increase susceptibility, disease severity, and hospitalization among older adults.