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Which complications can make influenza especially dangerous for older adults?

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Influenza virus — influenza A colored transmission electron micrograph showing influenza viruses (red) at the outer surface of a host cell.

Influenza is particularly dangerous for older adults primarily due to age-related declines in immune system function, which leave individuals more susceptible to infection and less capable of mounting a robust defense.12

A major complication that makes influenza especially hazardous is the increased susceptibility to secondary bacterial infections, most notably pneumonia. Specifically, an acute influenza attack can increase the body's vulnerability to Streptococcus pneumoniae, leading to severe respiratory complications.3

Furthermore, older adults often manage underlying chronic health conditions that can further weaken their immune response. In some cases, these conditions may render individuals more vulnerable to severe inflammatory reactions, such as a cytokine storm, which can result in organ failure. Because immunity naturally fades with age, older adults are encouraged to utilize specialized high-dose or adjuvanted influenza vaccines to help generate a stronger protective response against these life-threatening complications.12