Flu is a disease of all ages, with worst complications and risk of death in babies and the elderly, but people of all ages can get very sick or be hospitalized.
The CDC recommends:
Vaccination to prevent influenza is particularly important for persons who are at increased risk for severe complications from influenza, or at higher risk for influenza-related outpatient, ED, or hospital visits. When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to the following persons who do not have contraindications (no hierarchy is implied by order of listing):
- ll children aged 6 through 59 months;
- all persons aged ≥50 years;
- adults and children who have chronic pulmonary (including asthma) or cardiovascular (except isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus);
- persons who have immunosuppression (including immunosuppression caused by medications or by HIV infection);
- women who are or will be pregnant during the influenza season;
- children and adolescents (aged 6 months–18 years) who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye syndrome after influenza virus infection;
- residents of nursing homes and other long-term care facilities;
- American Indians/Alaska Natives; and
- persons who are extremely obese (BMI ≥40).
The reasons for this are countless, if you can handle it read the article in the above link.
So in short: people at risk of complications of flu. "Normal" people can handle a "normal" flu very well. An example of how things can go wrong is the spanish flu where healthy mid-aged people where more vulnerable.
This is for the USA. I'm from Holland and we use almost the same criteria, except for the extreme obese and only for persons aged >60 years. Also health professionals get a shot. AND we don't recommend giving the vaccine to children/babies! Only in some cases with bowel disease.
Hope this makes sense.
No you should not unless you are chronically sick. This research proves that. http://flushotcanada.blogspot.ca The CDC will tell you otherwise, and doctors who's training is guided by the Industry will as well.