Influenza: Prevention
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The Centers for Disease Control and Prevention recommend that people get an influenza vaccine injection each year before flu season starts. In the United States, flu season typically runs from late December to early March. Vaccines should be received two to six weeks prior to the onset of flu season to allow the body enough time to establish immunity. Adults need only one dose of the yearly vaccine, but children under nine years of age who have not previously been immunized should receive two doses, with a month between each dose.
Each season's flu vaccine contains three virus strains that are the most likely to be encountered in the coming flu season. When there is a good match between the anticipated flu strains and the strains used in the vaccine, the vaccine is 70–90% effective in people under 65. Because immune response diminishes somewhat with age, people over 65 may not receive the same level of protection from the vaccine, but even if they do contract the flu, the vaccine diminishes the severity and helps prevent complications.
The virus strains used to make the vaccine are inactivated and will not cause the flu. In the past, flu symptoms were associated with vaccine preparations that were not as highly purified as modern vaccines, not to the virus itself. In 1976, there was a slightly increased risk of developing Guillain-Barré syndrome, a very rare disorder, associated with the swine flu vaccine. This association occurred only with the 1976 swine flu vaccine preparation and has never recurred.
Serious side effects with modern vaccines are extremely unusual. Some people experience a slight soreness at the point of injection, which resolves within a day or two. People who have never been exposed to influenza, particularly children, may experience one to two days of a slight fever, tiredness, and muscle aches. These symptoms start within six to 12 hours after the vaccination.
It should be noted that certain people should not receive influenza vaccine. Infants six months and younger have immature immune systems and will not benefit from the vaccine. Since the vaccines are prepared using hen eggs, people who have severe allergies to eggs or other vaccine components should not receive the influenza vaccine. As an alternative, they may receive a course of amantadine or rimantadine, which are also used as a protective measure against influenza. Other people who might receive these drugs are those that have been immunized after the flu season has started or who are immunocompromised, such as people with advanced HIV disease. Amantadine and rimantadine are 70-90% effective in preventing influenza.
Certain groups are strongly advised to be vaccinated because they are at risk for influenza-related complications:
- all people 65 years and older
- residents of nursing homes and chronic-care facilities, regardless of age
- adults and children who have chronic heart or lung problems, such as asthma
- adults and children who have such chronic metabolic diseases as diabetes and renal dysfunction, as well as severe anemia or inherited hemoglobin disorders
- children and teenagers who are on long-term aspirin therapy
- women who will be in their second or third trimester of pregnancy during flu season or women who are nursing
- anyone who is immunocompromised, including HIV-infected persons; cancer patients; organ transplant recipients; and patients receiving steroids, chemotherapy, or radiation therapy
- anyone in contact with the above groups, such as teachers, care givers, health care personnel, and family members
- travelers to foreign countries
An individual need not be in one of the at-risk categories listed above, however, to receive a flu vaccination. Anyone who wants to forego the discomfort and inconvenience of an influenza attack may receive the vaccine.
— Julia Barrett
