This article is from the Childhood Vaccinations FAQ, by Lynn Gazis-Sax firstname.lastname@example.org with numerous contributions by others.
It is recommended for people who are over 65 and for people with
various chronic illnesses, particularly those affecting the lungs
(including asthma) or the heart. Candidates among children include
similar groups to those for pneumococcal vaccine: sickle cell, chronic
renal and metabolic disease, diabetes, chronic pulmonary disease,
long-term aspirin therapy, and significant cardiac disease (Catalana).
In the US, the rate of vaccination for influenza in the groups for
whom the vaccine is recommended is only 20%. Among children, the rate
is 1-7% (Catalana).
The antiviral drugs amantadine and rimantadine are also effective
against influenza A, but not influenza B.