Why should people get vaccinated against the flu?
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, but millions of people get the flu every year, 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. During flu season, flu viruses circulate at higher levels in the U.S. population. (“Flu season” in the United States 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 with seasonal flu and spreading it to others. When more people get vaccinated against the flu, less flu can spread 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 the use of injectable influenza vaccines (including inactivated influenza vaccines and recombinant influenza vaccines) during 2020-2021.
Quadrivalent flu vaccines include:
- Quadrivalent flu shots are approved for use in different age groups.
- 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 people 18 through 64 years of age.
- A quadrivalent flu shot containing virus grown in cell culture, which is approved for people 4 years of age and older.
Who should get vaccinated this season?
Who Should Not Be Vaccinated?
CDC recommends use of the flu shot (inactivated influenza vaccine or IIV) and the recombinant influenza vaccine (RIV). Different flu vaccines are approved for use in different groups of people. Factors that can determine a person’s suitability for vaccination, or vaccination with a particular vaccine, include a person’s age, health (current and past) and any allergies to flu vaccine or its components.
When should I get vaccinated?
Flu vaccination should begin soon after vaccine becomes available, if possible by October. However, as long as flu viruses are circulating, vaccination should continue to be offered throughout the flu season, even in January or later. While seasonal influenza outbreaks can happen as early as October, during most seasons influenza activity peaks in January or later. Since it takes about two weeks after vaccination for antibodies to develop in the body that protect against influenza virus infection, it is best that people get vaccinated so they are protected before influenza begins spreading in their community.
Flu vaccine is produced by private manufacturers, and the timing of availability depends on when production is completed. Shipments began in August and will continue throughout October and November until all vaccine is distributed.
Where can I get a flu vaccine?
Flu vaccines are offered in many locations, including doctor’s offices, clinics, health departments, pharmacies and college health centers, as well as by many employers, and even in some schools.
Even if you don’t have a regular doctor or nurse, you can get a flu vaccine somewhere else, like a health department, pharmacy, urgent care clinic, and often your school, college health center, or workplace.
The following Vaccine Locator is a useful tool for finding vaccine 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 flu 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 the age and health status of the person being vaccinated, and also the similarity or “match” 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. However, 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 (called cross-protection) against different but related influenza viruses. For more information about vaccine effectiveness, visit How Well Does the Seasonal Flu Vaccine Work?
Influenza vaccine effectiveness (VE) can vary from year to year and among different age and risk groups. For more information about vaccine effectiveness, visit How Well Does the Seasonal Flu Vaccine Work? For information specific to this season, visit About the Current Flu Season.
What are the benefits of flu vaccination?
While how well the flu vaccine works can vary, there are a lot of reasons to get a flu vaccine each year.
- Flu vaccination can keep you from getting sick with flu.
- Flu vaccination can reduce the risk of flu-associated hospitalization, including among children and older adults.
- A 2014 study* showed that flu vaccine reduced children’s risk of flu-related pediatric intensive care unit (PICU) admission by 74% during flu seasons from 2010-2012.
- Another study published in the summer of 2016 showed that people 50 years and older who got a flu vaccine reduced their risk of getting hospitalized from flu by 57%.
- Flu vaccination is an important preventive tool for people with chronic health conditions.
- Vaccination was associated with lower rates of some cardiac events among people with heart disease, especially among those who had had a cardiac event in the past year.
- Flu vaccination also has been shown to be 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. (Mom passes antibodies onto the developing baby during her pregnancy.)
- A study that looked at flu vaccine effectiveness in pregnant women found that vaccination reduced the risk of flu-associated acute respiratory infection by about one half.
- There are studies that show that flu vaccine in a pregnant woman can reduce the risk of flu illness in her baby by up to half. This protective benefit was observed for up to four months after birth.
- Flu vaccination also may make your illness milder if you do get sick.
- 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.
*References for the studies listed above can be found at Publications on Influenza Vaccine Benefits. Also see the What are the Benefits of Flu Vaccination?[237 KB, 2 pages] fact sheet.