Which patient population is at higher risk for severe illness from influenza?

The correct choice highlights that older adults and individuals with chronic conditions are at a significantly higher risk for severe illness from influenza. This is largely due to the age-related decline in the immune response, which makes it harder for older adults to effectively fight off infections. Chronic conditions, such as asthma, diabetes, heart disease, and lung diseases, can further compromise the immune system and significantly increase susceptibility to severe outcomes when infected with influenza.

In contrast, healthy young adults generally have a more robust immune response, enabling them to manage influenza infections more effectively. While infants and toddlers are also at risk due to their developing immune systems, the combination of age and existing health conditions in older adults creates a particularly vulnerable group. Thus, it is critical to prioritize preventative measures such as vaccination for these populations to reduce the incidence of severe illness and complications associated with influenza.