Flu Shot Facts
The single best way to protect against the flu is to get vaccinated each year.
How do flu vaccines work?
Flu vaccines cause antibodies to develop in the body about two weeks after vaccination. These antibodies provide protection against infection with the viruses that are in the vaccine.
The seasonal flu vaccine protects against the influenza viruses that research indicates will be most common during the upcoming season. Traditional flu vaccines (called "trivalent" vaccines) are made to protect against three flu viruses; an influenza A (H1N1) virus, an influenza A (H3N2) virus, and an influenza B virus. There are also flu vaccines made to protect against four flu viruses (called "quadrivalent" vaccines). These vaccines protect against the same viruses as the trivalent vaccine and an additional B virus.
What kinds of flu vaccines are available?
There are several flu vaccine options for the 2015-2016 flu season. Traditional flu vaccines made to protect against three different flu viruses (called "trivalent" vaccines) are available. In addition, flu vaccines made to protect against four different flu viruses (called "quadrivalent" vaccines) also are available.
Trivalent flu vaccine protects against two influenza A viruses (an H1N1 and an H3N2) and an influenza B virus. The following trivalent flu vaccines are available:
1. Standard-dose trivalent shots that are manufactured using virus grown in eggs. There are several different flu shots of this type available, and they are approved for people of different ages. Some are approved for use in people as young as 6 months of age. Most flu shots are given with a needle. One standard dose trivalent shot also can be given with a jet injector, for persons aged 18 through 64 years.
2. A high-dose trivalent shot, approved for people 65 and older.
3. A trivalent shot containing virus grown in cell culture, which is approved for people 18 and older.
4. A recombinant trivalent shot that is egg-free, approved for people 18 years and older.
The quadrivalent flu vaccine protects against two influenza A viruses and two influenza B viruses. The following quadrivalent flu vaccines are available:
1. A quadrivalent flu shot that is manufactured using virus grown in eggs. There are several different flu shots of this type available, and they are approved for people of different ages. Some are approved for use in people as young as 6 months of age.
2. An intradermal quadrivalent shot, which is injected into the skin instead of the muscle and uses a much smaller needle than the regular flu shot. It is approved for people 18 through 64 years of age.
3. A quadrivalent nasal spray vaccine, approved for people 2 through 49 years of age.
Are any of the available flu vaccines recommended over others?
For the 2015-2016 flu season, ACIP recommends annual influenza vaccination for everyone 6 months and older with either LAIV or IIV with no preference expressed when either vaccine is available.
There are many vaccine options to choose from, including high-dose vaccine, intradermal vaccine and the regular flu shot. The most important thing is for all people 6 months and older to get a flu vaccine every year. If you have questions about which vaccine is best for you, talk to your doctor or other health care professional.
Who should get vaccinated this season?
Everyone 6 months of age and older should get a flu vaccine every season. This recommendation has been in place since February 24, 2010 when CDC's Advisory Committee on Immunization Practices (ACIP) voted for "universal" flu vaccination in the United States to expand protection against the flu to more people. Vaccination to prevent influenza is particularly important for people who are at high risk of serious complications from influenza.
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