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Why should people get vaccinated against the flu?
Influenza is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and lungs. It can cause mild to severe illness and, at times, can lead to death. Every flu season is different, and influenza infection can affect people differently, but millions of people get the flu, hundreds of thousands of people are hospitalized, and thousands or tens of thousands of people die from flu-related causes every year. Even healthy people can get very sick from the flu and spread it to others.

CDC estimates that flu-related hospitalizations since 2010 ranged from 140,000 to 710,000, while flu-related deaths are estimated to have ranged from 12,000 to 56,000. Flu season can begin as early as October and last as late as May. An annual seasonal flu vaccine is the best way to reduce your risk of getting sick and spreading the flu to others. When more people get vaccinated against the flu, less flu spreads through that community.

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?
CDC recommends use of injectable influenza vaccines (including inactivated influenza vaccines and recombinant influenza vaccines) during 2017-2018. The nasal spray flu vaccine (live attenuated influenza vaccine or LAIV) should not be used during this flu season. Both trivalent and quadrivalent vaccines will be available.

Trivalent vaccines include:
  • Standard-dose trivalent shots that are manufactured using virus grown in eggs. Different flu shots are approved for different age groups. Most flu shots are given in the arm with a needle. One trivalent vaccine formulation can be given with a jet injector, for people aged 18-64.
  • A high-dose trivalent shot, approved for people 65 and older.
  • A recombinant trivalent shot that is egg-free, approved for people 18 and older, including pregnant women.
  • A trivalent flu shot made with adjuvant (an ingredient that helps create a stronger immune response in the patient’s body), approved for people 65 and older (new this season).

Quadrivalent flu vaccines include:
  • Quadrivalent flu shots approved for use in different age groups, including children as young as 6 months.
  • An intradermal quadrivalent flu 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 ages 18-64.
  • A quadrivalent flu shot containing virus grown in cell culture, which is approved for people 4 years of age and older.
  • A recombinant quadrivalent flu shot approved for people 18 years of age and older, including pregnant women (new this season).
Are any of the available flu vaccines recommended over others?
There are many vaccine options to choose from, but 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.

For the 2017-2018 flu season, the Advisory Committee on Immunization Practices recommends annual influenza vaccination for everyone 6 months and older with either the inactivated influenza vaccine (IIV) or the recombinant influenza vaccine (RIV). The nasal spray flu vaccine (live attenuated influenza vaccine or LAIV) should not be used during 2017-2018. There is no preference for one vaccine over another among the recommended, approved injectable influenza vaccines.
Who should get vaccinated this season?
Everyone 6 months of age and older should get a flu vaccine every season. Vaccination to prevent influenza is particularly important for people who are at high risk of serious complications from influenza. See People at High Risk of Developing Flu-Related Complications for a full list of age and health factors that confer increased risk. More information is available here.

Different flu vaccines are approved for use in different groups of people. Factors that can determine a person’s suitability for vaccination, or use of a particular vaccine, include age, health, and potential allergies to flu vaccine or its components. Learn more here.

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 to develop in the body that protect against flu, 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, if possible. Getting vaccinated later, however, can still be beneficial and vaccination should continue to be offered throughout the 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.

Where can I get a flu vaccine?
Flu vaccines are offered in many locations, including doctor’s offices, clinics, pharmacies and health centers, as well as by many employers, and even in some schools. Even if you don’t have a regular doctor, you can get a flu vaccine somewhere else, like a pharmacy, urgent care clinic, and often your school, health center, or workplace.

Click here to find a vaccine provider in your area.

Why do I need a flu vaccine every year?
A flu vaccine is needed every season for two reasons. First, the body’s immune response from vaccination declines over time, so an annual vaccine is needed for optimal protection. Second, because flu viruses are constantly changing, the formulation of the vaccine is reviewed each year and sometimes updated to keep up with changing flu viruses. For the best protection, everyone 6 months and older should get vaccinated annually.

Does flu vaccine work right away?
No. It takes about two weeks after vaccination for antibodies to develop in the body and provide protection against influenza virus infection. That’s why it’s better to get vaccinated early in the fall, before the flu season really gets under way.

Can I get seasonal flu even though I got a flu vaccine this year?
Yes. There is still a possibility you could get the flu even if you got vaccinated. The ability of flu vaccine to protect a person depends on various factors, including age, health, and the similarity between the viruses used to make the vaccine and those circulating in the community. If the viruses in the vaccine and the influenza viruses circulating in the community are closely matched, vaccine effectiveness is higher. If they are not closely matched, vaccine effectiveness can be reduced. It’s important to remember that even when the viruses are not closely matched, the vaccine can still protect many people and prevent  flu-related complications. Such protection is possible because antibodies made in response to the vaccine can provide some protection against different but related influenza viruses.

What are the benefits of being vaccinated?
While how well the flu vaccine works can vary, there are many reasons to get a flu vaccine each year.
  • Flu vaccination can keep you from getting sick with flu and may make your illness milder if you do get sick.
  • Flu vaccination can reduce the risk of flu-associated hospitalization, including among children and older adults.
  • Flu vaccination is an important preventive tool for people with chronic health conditions.
    • Flu vaccination has been associated with lower rates of some cardiac (heart) events among people with heart disease, especially among those who experienced a cardiac event in the past year.
    • Flu vaccination also has been associated with reduced hospitalizations among people with diabetes (79%) and chronic lung disease (52%).
  • Vaccination helps protect women during and after pregnancy. Getting vaccinated can also protect a baby after birth from flu, because mothers pass antibodies to their babies during her pregnancy.
  • A 2017 study was the first of its kind to show that flu vaccination can significantly reduce a child’s risk of dying from influenza.
  • Getting vaccinated yourself also protects people around you, including those who are more vulnerable to serious flu illness, like babies and young children, older people, and people with certain chronic health conditions.

For even more information about influenza vaccines, visit https://www.cdc.gov/flu/protect/keyfacts.htm