FAQs About the Seasonal Flu Vaccine
- What is flu vaccine?
- Who should get flu vaccine and when?
- Who should not get the flu vaccine?
- What are the side effects of the flu vaccine?
What is flu vaccine?
The standard flu vaccine (or, the “flu shot”) is made from flu viruses that have been grown on fertilized chicken eggs. The viruses are killed during manufacturing, a process known as “inactivation.” These inactivated viruses are a source of proteins or antigens that trigger a protective antibody response when the vaccine is injected into the arm or thigh muscle. Antibodies against flu viruses begin to appear one to two weeks after getting the flu shot and last for months, and perhaps even up to one year.
In the past, flu vaccine protected you against three strains of seasonal flu and was termed “trivalent influenza vaccine” (TIV). Beginning with the 2013-2014 season, PAMF will transition largely to flu shot vaccines that contain four strains of flu viruses (another B strain will be added). Thus, “quadrivalent influenza vaccines” (QIV) will contain two A strains and two B strains. Scientists added the second B strain because predicting which flu B strain would circulate in any given season proved difficult. The flu nasal spray (FluMistTM) will also be quadrivalent. Some PAMF divisions will also order a small supply of TIV flu shot vaccine for patients who want to be vaccinated in early September because the QIV will arrive a little later in September than usual. Both TIV and QIV flu shot products will be mostly FluzoneTM.
Two other flu shot vaccines will be available. First, the high-dose flu vaccine for persons 65 years and older will again be available in the 2013-2014 season. Known as FluzoneTM High-Dose. It contains four times as much antigen as the standard flu vaccine. Although it boosts the antibody level in seniors more than the standard vaccine, we do not know yet if it is more effective in preventing the flu or its complications. The high-dose vaccine is also slightly more likely to cause injection-site pain and fever, and for the 2013-2014 season will be trivalent only. Second, a recombinant flu shot vaccine (FlublokTM) will be available through our allergy departments for patients 18-49 years with serious allergies to eggs. Unlike the standard flu shot or nasal spray, the recombinant vaccine is not manufactured using eggs.
All vaccines at PAMF will be thimerosal and latex free.
Because vaccine strains often change from one year to the next and immunity wanes, the flu vaccine must be given every year.
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Who should get flu vaccine and when?
The easy answer is that almost everyone 6 months of age and older should get the flu vaccine, and they should get it preferably in September or October, but they can be vaccinated throughout the flu season. Special efforts should be made to vaccinate the following persons because they are either at risk for complications from the flu, or they might give the flu to someone who is at risk:
- Women who are or will be pregnant during the flu season
- Children younger than 5 years, especially children younger than 2
- Children on chronic aspirin therapy
- People 50 years and older
- Persons who are morbidly obese
- Native American and Alaskan natives
- Persons of any age with certain chronic medical conditions (see recommendations on Centers for Disease Control and Prevention website (CDC) for more information)
- Persons who live in nursing homes and other long-term care facilities
- Persons who live with or care for those at high risk for complications from flu, including:
- Health care workers
- Household contacts of persons at high risk for complications from the flu
- Household contacts and out of home caregivers of children less than 6 months of age (these children are too young to be vaccinated)
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Who should not get the flu vaccine?
Flu vaccine is extremely safe for the vast majority of persons, including breastfeeding and pregnant women (pregnant women may receive the flu shot but should not receive the nasal spray vaccine). However, several groups should exercise caution:
- Persons with a history of severe allergic reaction to eggs or the flu vaccine itself should consult a physician before receiving flu vaccine. According to CDC, if an allergic reaction to eggs is only hives and nothing more serious, a person may receive the flu shot [not the nasal spray vaccine] if a physician is present who is equipped to treat a serious allergic reaction and the person is observed for at least 30 minutes. Alternatively, these patients, if aged 18-49 years, could given the new recombinant flu vaccine. More serious reactions require consultation with an allergist before flu vaccination, and again the recombinant vaccine could be used if the age is appropriate.
- Anyone who is moderately or severely ill (e.g. with a high fever) should defer flu vaccination until resolution of the illness.
- Children under 6 months of age should not get the flu vaccine because it is ineffective in this age group.
- Persons with a history of Guillain-Barre syndrome should consult their physician before receiving the flu vaccine.
- Pregnant women should not receive the flu nasal spray because it is a live vaccine. They should get a flu shot instead.
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What are the side effects of the flu vaccine?
The flu vaccine rarely causes serious adverse effects. The most common reaction to the flu shot is mild soreness at the site of injection which is well tolerated. Flu-like symptoms, such as fever and muscle aches, occasionally occur six to 12 hours after receiving the flu shot and last one to two days. However, these symptoms are very rare. The live, intranasal flu vaccine can cause symptoms of a head cold, and the high-dose flu vaccine is more likely to cause injection-site pain or fever.
Guillain-Barre syndrome (GBS), an acute paralytic illness, was linked to the swine flu vaccine of 1976. Since 1976, studies have failed to show a similar association between flu vaccines and GBS. It is estimated that at most one excess case of GBS per million persons vaccinated may be attributable to the flu vaccine. The extremely low incidence of GBS stands in contrast to the many hospitalizations and deaths prevented by the flu vaccine.
Last updated 8/2013
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