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Influenza Vaccine

The single best way to protect against the flu is to get vaccinated each year.

Influenza is a serious disease that can lead to hospitalization and sometimes even death. Every flu season is different, and influenza infection can affect people differently. Even healthy people can get very sick from the flu and spread it to others. Over a period of 31 seasons between 1976 and 2007, estimates of flu-associated deaths in the United States range from a low of about 3,000 to a high of about 49,000 people. During recent flu seasons, between 80% and 90% of flu-related deaths have occurred in people 65 years and older. "Flu season" in the United States can begin as early as October and last as late as May.

During this time, flu viruses are circulating at higher levels in the U.S. population. An annual seasonal flu vaccine (either the flu shot or the nasal spray flu vaccine) is the best way to reduce the chances that you will get seasonal flu and spread it to others. When more people get vaccinated against the flu, less flu can spread through that community.

In 2017, a study in Pediatrics was the first of its kind to show that flu vaccination also significantly reduced a child's risk of dying from influenza. The more people who get vaccinated, the more people will be protected from flu, including older people, very young children, pregnant women, and people with certain long-term health conditions who are more vulnerable to serious flu complications

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.

When should I get vaccinated?

You should get a flu vaccine before flu begins spreading in your community. It takes about two weeks after vaccination for antibodies that protect against flu to develop in the body, so make plans to get vaccinated early in fall, before flu season begins. CDC recommends that people get a flu vaccine by the end of October. Getting vaccinated later, however, can still be beneficial and vaccination should continue to be offered throughout flu season, even into January or later.

Children who need two doses of vaccine to be protected should start the vaccination process sooner, because the two doses must be given at least four weeks apart.

What kinds of flu vaccines are available? 

There are several flu vaccine options for the 2018-19 flu season. This season, injectable flu vaccines (flu shots) and nasal spray are recommended.

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.

  • Standard dose flu shots. These are given into the muscle. They are usually given with a needle, but two (Afluria and Afluria Quadrivalent) can be given to some people (those aged 18 through 64 years) with a jet injector.
  • High-dose shots for older people.
  • Shots made with adjuvant for older people.
  • Shots made with virus grown in cell culture.
  • Shots made using a vaccine production technology (recombinant vaccine) that does not require the use of flu virus.
  • Live attenuated influenza vaccine (LAIV) – or the nasal spray vaccine – is also an option for use during the 2018-2019 season for persons whom it is otherwise appropriate.

Are any of the available flu vaccines recommended over others?

For the 2018-19 flu season, ACIP recommends annual influenza vaccination for everyone 6 months and older, with no preference expressed when vaccine is available. There are many vaccine options to choose from, including high-dose vaccine, intradermal vaccine, nasal spray 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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