Which age groups have the highest incidence of influenza?

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

While influenza can affect individuals of all ages, the highest incidence of the disease occurs among children and young adults.1

Although these groups experience the highest infection rates, it is important to note that the severity and fatality of the disease vary across the population. While outbreaks are generally most fatal to young children and the elderly, individuals between the ages of 20 and 40 may sometimes face unexpectedly high fatality rates due to a hyper-reaction of the immune system to new viral strains. Conversely, death from influenza complications, such as pneumonia or bronchitis, is most common among older individuals who may already be weakened by other health conditions.21