Influenza Vaccination: A Summary for Clinicians

Who Should Get Vaccinated?

Everyone 6 months of age and older should get an influenza (flu) vaccine every season with rare exception. CDC’s Advisory Committee on Immunization Practices has made this recommendation since the 2010-2011 flu season.

Vaccination to prevent flu and its potentially serious complications is particularly important for people who are at higher risk of developing serious flu complications. See People at Higher Risk of Developing Flu-Related Complications for a full list of age and health factors that confer increased risk.

More information is available at Who Needs a Flu Vaccine.

What are the influenza vaccine options this season?

CDC recommends use of any licensed, age-appropriate influenza vaccine during the 2021-2022 influenza season. Available influenza vaccines include quadrivalent inactivated influenza vaccine [IIV4], recombinant influenza vaccine [RIV4], or live attenuated influenza vaccine (LAIV4). No preference is expressed for any influenza vaccine over another.

Quadrivalent flu vaccines include:

  • Standard-dose quadrivalent influenza shots that are manufactured using virus grown in eggs.  These include Afluria Quadrivalent, Fluarix Quadrivalent, FluLaval Quadrivalent, and Fluzone Quadrivalent. Different influenza shots are licensed for different age groups. These four vaccines are approved for people 6 months of age and older. Most influenza shots are given in an arm muscle with a needle. One quadrivalent influenza shot (Afluria Quadrivalent) can be given either with a needle (for people aged 6 months and older) or with a jet injector (for people aged 18 through 64 years only).
  • A quadrivalent cell-based influenza shot (Flucelvax Quadrivalent) containing virus grown in cell culture, which is licensed for people 4 years and older. This vaccine is egg-free.
  • Recombinant quadrivalent influenza shot (Flublok Quadrivalent), an egg-free vaccine, approved for people 18 years and older.
  • quadrivalent flu shot using an adjuvant (an ingredient that helps create a stronger immune response), Fluad Quadrivalent, approved for people 65 years of age and older.
  • A quadrivalent high-dose influenza vaccine Fluzone High-Dose, which contains a higher dose of antigen to help create a stronger immune response, licensed for people 65 years and older.
  • A live attenuated influenza vaccine (FluMist Quadrivalent), which is given intranasally. This vaccine is approved for people 2 through 49 years of age. Live attenuated influenza vaccine should not be given to people who are pregnant, immunocompromised persons, and some other groups.
  • 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 2021-2022 flu season, and age indications for each vaccine are available in CDC’s Table: U.S. Influenza Vaccine Products for the 2021-2022 Season.
Are any of the available influenza vaccines recommended over others?

For the 2021-2022 flu season, the Advisory Committee on Immunization Practices (ACIP) recommends annual influenza (flu) vaccination for everyone 6 months and older with any licensed, influenza vaccine that is appropriate for the recipient’s age and health status, including inactivated influenza vaccine (IIV4), recombinant influenza vaccine (RIV4), or live attenuated nasal spray influenza vaccine (LAIV4) with no preference expressed for any one vaccine over another.

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.

When should I get vaccinated?

It’s best to be vaccinated before flu begins spreading in your community. September and October are generally good times to be vaccinated against flu. Ideally, everyone should be vaccinated by the end of October. However, even if you are not able to get vaccinated until November or later, vaccination is still recommended because flu most commonly peaks in February and significant activity can continue into May.

Additional considerations concerning the timing of vaccination for certain groups include:

  • Adults, especially those 65 years and older, should generally not get vaccinated early (in July or August) because protection may decrease over time, but early vaccination can be considered for any person who is unable to return at a later time to be vaccinated.
  • Children can get vaccinated as soon as vaccine becomes available, even if this is in July or August. Some children need two doses of flu vaccine. For those children it is recommended to get the first dose as soon as vaccine is available, because the second dose needs to be given at least 4 weeks after the first.
  • Early vaccination can also be considered for people who are in the third trimester of pregnancy, because this can help protect their infants during the first months of life (when they are too young to be vaccinated).
Vaccination for Children

Children 6 months of age and older are recommended to get an annual influenza vaccine. Children younger than 5 years old–especially those younger than 2– are at higher risk of developing serious influenza-related complications. An influenza vaccine offers the best protection against influenza and its potentially serious consequences, and also can reduce the spread of influenza to others.

Children can get vaccinated as soon as vaccines becomes available—even if this is in July or August.  Children  6 months to 8 years of age receiving their first influenza vaccine, or who have not previously received 2 or more doses in their lives, need two doses. For those children it is recommended to get the first dose as soon as vaccine is available, because the second needs to be given at least 4 weeks after the first.

For more information visit Flu & Young Children.

Vaccination for Adults

Everyone 6 months of age and older is recommended to get an annual influenza vaccine, including even healthy adults. Vaccination is especially important for people at higher risk of serious influenza complications or people who live with or care for people at higher risk for serious influenza complications.

Persons working in health care settings also should be vaccinated annually against influenza. Vaccination of health care professionals has been associated with reduced work absenteeism and with fewer deaths among nursing home patients.

People Who Should Not Be Vaccinated

Different influenza (flu) 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 flu vaccine or its components. For more information, visit Who Should and Who Should NOT get a Flu Vaccine.

Vaccination of People with a History of Egg Allergy

Most influenza vaccines are produced by growing influenza viruses in embryonated chicken eggs, and therefore contain trace amounts of egg protein. The cell-culture based inactivated vaccine (ccIIV4) and the recombinant influenza vaccine (RIV4) are egg-free.  People with egg allergy can receive any licensed influenza vaccine which is otherwise appropriate for their age and health status.  Those who have had a severe allergic reaction to egg (any symptom other than hives) should be vaccinated in a medical setting under supervision of a provider who can recognize and manage a severe allergic reaction, if a vaccine other than ccIIV4 or RIV4 is used. All vaccines should be administered in settings in which personnel and equipment for rapid recognition and treatment of anaphylaxis are available.

See Persons with a History of Egg Allergy for complete information to guide decision-making for vaccination of persons with egg allergy.

People with Allergies to Vaccine Components, or Allergic Reactions to Influenza Vaccines

A previous severe allergic reaction to a component of an influenza vaccine (with the exception of egg protein) is a contraindication to receipt of that vaccine and vaccines containing that component.  Vaccine components can be found in package inserts.

For people who have had an allergic reaction to a previous dose of an influenza vaccine, future receipt of that vaccine is contraindicated.  For other influenza vaccines, there will either be a contraindication or a precaution to future receipt.  Whether another influenza vaccine has a contraindication or precaution depends upon what vaccine was associated with the severe allergic reaction.  See current ACIP recommendations for further guidance.  If vaccination is elected when a precaution is present, it should occur in a medical setting under supervision of a provider who can recognize and manage a severe allergic reaction. Providers can also consider consultation with an allergist in such cases to help identify the vaccine component responsible for the severe allergic reaction.

Influenza Vaccines and Use of Influenza Antiviral Medications

Administration of inactivated influenza vaccine to persons receiving influenza antiviral drugs for treatment or chemoprophylaxis is acceptable.

Use of LAIV4 for persons who are receiving or who have recently received influenza antiviral medications has not been studied. But because LAIV4 contains live viruses that need to replicate in the nasopharynx in order to promote an immune response, it is conceivable that these medications might interfere with the effectiveness of LAIV4  The exact period of time during which this might occur is not known.  Based upon the half-lives of the different medications, interference might be possible

    • From 48 hours before to two weeks after LAIV4 administration for oseltamivir and zanamivir,
    • From 5 days before to two weeks after LAIV4 administration for oseltamivir and peramivir, and
    • From 17 days before to two weeks after LAIV4 administration for baloxavir

People who receive these medications during these periods before or after receipt of LAIV4 should be revaccinated with another appropriate influenza vaccine.  Time periods for which interference might be possible could be longer than those listed in the setting of medical conditions that delay clearance of medications.

Concurrent Administration of Influenza Vaccine With Other Vaccines

Inactivated and recombinant influenza vaccines may be administered concurrently or sequentially with other live or inactivated vaccines. Injectable vaccines given simultaneously should be administered at separate anatomic sites.

LAIV4 may be administered simultaneously with other inactivated or live vaccines. If not given simultaneously, then LAIV4 and other live vaccine should be spaced at least 4 weeks apart.

Current guidance for the use of COVID-19 vaccines states that these vaccines may be administered with other vaccines.  Providers should refer to current CDC and Advisory Committee on Immunization Practices (ACIP) recommendations and guidance for the use of COVID-19 vaccines  for up to date information on administration of these vaccines with other vaccines.

 

What Is CDC’s Position on Mandating Flu Vaccination for Health Care Workers?

The findings of a CDC review of related published literature indicate that influenza vaccination of health care personnel can enhance patient safety. 1,2

CDC conducts science-based investigations, research, and public health surveillance both nationally and internationally. CDC adopts recommendations that are made by the Advisory Committee for Immunization Practices. These recommendations may be considered by state and other Federal agencies when making or enforcing laws. CDC also has infection control recommendations for health care settings. However, CDC does not issue any requirements or mandates for state agencies, health systems, or health care workers regarding infection control practices, including influenza vaccination or the use of masks.

Some employers require certain immunizations. Hospitals, for example, may require some staff to get a flu vaccine or hepatitis B vaccine or take other precautions such as the use of masks.

To find out more about the laws in your state and  to contact your state health department through Public Health Resources: State Health Departments.

State Immunization Laws for Healthcare Workers and Patients and Vaccines and Immunizations: Basics and Common Questions National Center for Immunization and Respiratory Diseases have more information. For more information, updates, and access to free materials to assist with educating staff and patients about the impact of influenza and the benefits of vaccination, visit CDC Seasonal Influenza (Flu) or call the National Immunization Hotline at (800) 232-2522 (English), (800) 232-0233 (español), or (800) 243-7889 (TTY).

For Your Patients

VIS are information sheets produced by CDC that explain both the benefits and risks of a vaccine to vaccine recipients.