Influenza (cont.)

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Who should receive the flu vaccine, and who has the highest risk factors? When should someone get the flu shot?

In the United States, the flu season usually occurs from about November until April. Officials have decided each new flu season will start each year on Oct. 4. Typically, activity is very low until December, and peak activity most often occurs between January and March. Ideally, the conventional flu vaccine should be administered between September and mid-November. It takes about one to two weeks after vaccination for antibodies against influenza to develop and provide protection. The CDC has published a summary list of their current recommendations of who should get the current vaccine:

Summary of influenza vaccination recommendations

  • All people 6 months and older should be vaccinated annually, unless they have a rare and specific contraindication (for example, severe egg allergy, previous severe reaction to the vaccine, certain neurologic problems).
  • Protection of people at higher risk for influenza-related complications should continue to be a focus of vaccination efforts as providers and programs transition to routine vaccination of all people 6 months and older.
  • When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to people who
    • are 6 months to 4 years (59 months) of age;
    • are 50 years of age and older;
    • have chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorder (including diabetes mellitus);
    • are immunosuppressed (including immunosuppression caused by medications or by human immunodeficiency virus);
    • are or will be pregnant during the influenza season;
    • are 6 months to 18 years of age and receiving long-term aspirin therapy and who therefore might be at risk for experiencing Reye's syndrome after influenza virus infection;
    • are residents of nursing homes and other chronic-care facilities;
    • are American Indians/Alaska natives;
    • are morbidly obese (body mass index is 40 or greater);
    • are health-care professionals;
    • are household contacts and caregivers of children aged younger than 5 years and adults aged 50 years and older, with particular emphasis on vaccinating contacts of children aged younger than 6 months;
    • are household contacts and caregivers of people with medical conditions that put them at higher risk for severe complications from influenza.

As each flu season progresses and as the CDC refines its data from previous flu seasons and pandemics, this summary may be modified. The CDC publishes routine updates about the flu at and at

Medically Reviewed by a Doctor on 1/15/2015

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