Influenza (flu) vaccines (often called “flu shots”) are vaccines that protect against the four influenza viruses that research indicates will be most common during the upcoming season. Most flu vaccines are “flu shots” given with a needle, usually in the arm, but there also is a nasal spray flu vaccine.
The composition of flu vaccines has been updated for the 2023-2024 flu season.
Yes. There are different flu vaccine manufacturers and multiple flu vaccines that are licensed and recommended for use in the United States. Fluzone High-Dose Quadrivalent vaccine, Flublok Quadrivalent recombinant flu vaccine and Fluad Quadrivalent adjuvanted flu vaccine.
There are many flu 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. More information on approved flu vaccines for the current flu season, and age indications for each vaccine are available in CDC’s Table: U.S. Influenza Vaccine Products for the 2023-2024 Season.
Everyone 6 months and older in the United States, with rare exception, should get an influenza (flu) vaccine every season. CDC’s Advisory Committee on Immunization Practices has made this “universal” recommendation since the 2010-2011 influenza season.
Vaccination to prevent influenza and its potentially serious complications is particularly important for people who are at higher risk of developing serious influenza complications. A full list of age and health factors that are associated with increased risk is available at People at Higher Risk of Developing Flu-Related Complications.
More information is available at Who Needs a Flu Vaccine.
Different influenza vaccines are approved for use in people in different age groups. In addition, some vaccines are not recommended for certain 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 influenza vaccine or its components. More information is available at Who Should and Who Should NOT get a Flu Vaccine.
Yes, for some people. There are three flu vaccines that are preferentially recommended for people 65 years and older. These are Fluzone High-Dose Quadrivalent vaccine, Flublok Quadrivalent recombinant flu vaccine or Fluad Quadrivalent adjuvanted flu vaccine. On June 22, 2022, CDC’s Advisory Committee on Immunization Practices (ACIP) voted unanimously to preferentially recommend these vaccines over standard-dose unadjuvanted flu vaccines. This recommendation was based on a review of available studies which suggests that, in this age group, these vaccines are potentially more effective than standard dose unadjuvanted flu vaccines. There is no preferential recommendation for people younger than 65 years.
If one of the three preferentially recommended flu vaccines for people 65 and older is not available at the time of administration, people in this age group should get an age-appropriate standard-dose flu vaccine instead.
Influenza (flu) vaccine effectiveness (VE) can vary. The protection provided by a flu vaccine varies from season to season and depends in part on the age and health status of the person getting the vaccine and the similarity or “match” between the viruses in the vaccine and those in circulation. During years when the flu vaccine match is good, it is possible to measure substantial benefits from flu vaccination in terms of preventing flu illness and complications. However, the benefits of flu vaccination will still vary, depending on characteristics of the person being vaccinated (for example, their health and age), what flu viruses are circulating that season and, potentially, which type of flu vaccine was used. More information is available at Vaccine Effectiveness – How well does the Flu Vaccine Work.
There are many reasons to get an influenza (flu) vaccine each year.
Below is a summary of the benefits of flu vaccination and selected scientific studies that support these benefits.
Despite the many benefits offered by flu vaccination, only about half of Americans get an annual flu vaccine. During an average flu season, flu can cause millions of illnesses, hundreds of thousands of hospitalizations and tens of thousands of deaths. Many more people could be protected from flu if more people got vaccinated.
*References for the studies listed above can be found at Publications on Influenza Vaccine Benefits.
Common side effects from a flu shot include soreness, redness, and/or swelling where the shot was given, headache (low grade), fever, nausea, muscle aches, and fatigue. The flu shot, like other injections, can occasionally cause fainting.
Life-threatening allergic reactions to flu shots are very rare. Signs of serious allergic reaction can include breathing problems, hoarseness or wheezing, hives, paleness, weakness, a fast heartbeat, or dizziness. If they do occur, it is usually within a few minutes to a few hours after receiving the shot. These reactions can occur among persons who are allergic to something that is in the vaccine, such as egg protein or other ingredients. While severe reactions are uncommon, you should let your doctor, nurse, clinic, or pharmacist know if you have a history of allergy or severe reaction to influenza vaccine or any part of flu vaccine.
There is a small possibility that flu vaccine could be associated with Guillain-Barré syndrome, generally no more than 1 or 2 cases per million people vaccinated. This is much lower than the risk of severe complications from flu, which can be prevented by flu vaccine.
Call a doctor or get to a doctor right away.
Tell your doctor what happened, the date and time it happened, and when you got the flu shot.
Ask your doctor, nurse, or health department to file a Vaccine Adverse Event Reporting System (VAERS) form, or call VAERS at 1-800-822-7967. Reports are welcome from all concerned individuals: patients, parents, health care providers, pharmacists and vaccine manufacturers.
Flu vaccine side effects are generally mild and go away on their own within a few days. Some side effects that may occur from a flu shot include soreness, redness, and/or swelling where the shot was given, headache (low grade), fever, nausea, muscle aches, and fatigue. The flu shot, like other injections, can occasionally cause fainting.
There are several reasons why someone might get flu symptoms even after they have been vaccinated against flu.
Some people who get vaccinated may still get sick. However, flu vaccination has been shown in several studies to reduce severity of illness in people who get vaccinated but still get sick:
In addition, it’s important to remember that flu vaccine protects against three or four different viruses and multiple viruses usually circulate during any one season. For these reasons, CDC continues to recommend flu vaccination for everyone 6 months and older even if vaccine effectiveness against one or more viruses is reduced.
People with egg allergy may get any vaccine (egg-based or non-egg-based) that is otherwise appropriate for their age and health status. Previously, it was recommended that people with severe allergy to egg (those who have had any symptom other than hives with egg exposure) be vaccinated in an inpatient or outpatient medical setting. Beginning with the 2023-2024 season, additional safety measures are no longer recommended for flu vaccination of people with an egg allergy beyond those recommended for receipt of any vaccine, regardless of the severity of previous reaction to egg. All vaccines should be given in settings where allergic reactions can be recognized and treated quickly.