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Influenza Vaccination: A Summary for Clinicians

Who Should Get Vaccinated?

All persons 6 months and older should be vaccinated annually.

Persons at Risk for Medical Complications Attributable to Severe Influenza

Vaccination to prevent influenza is particularly important for persons who are at increased risk for severe complications from influenza, or at higher risk for influenza-related outpatient, ED, or hospital visits. When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to the following persons (no hierarchy is implied by order of listing):

  • all children aged 6 through 59 months;
  • all persons aged 50 years and older;
  • adults and children who have chronic pulmonary (including asthma) or cardiovascular (except isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus);
  • persons who have immunosuppression (including immunosuppression caused by medications or by HIV infection);
  • women who are or will be pregnant during the influenza season;
  • children and adolescents (aged 6 months through 18 years) who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye's syndrome after influenza virus infection;
  • residents of nursing homes and other long-term care facilities;
  • American Indians/Alaska Natives; and
  • persons who are morbidly obese (body mass index of 40 or greater).
Persons Who Live With or Care for Persons at High Risk for Influenza-Related Complications

All persons aged 6 months and older should be vaccinated annually. Continued emphasis should be placed on vaccination of persons who live with or care for persons at higher risk for influenza-related complications. When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to persons at higher risk for influenza-related complications listed above, as well as these persons:

  • health-care personnel;
  • household contacts (including children) and caregivers of children aged 59 months and older (i.e., aged younger than 5 years) and adults aged 50 years and older, with particular emphasis on vaccinating contacts of children aged younger than 6 months; and
  • household contacts (including children) and caregivers of persons with medical conditions that put them at high risk for severe complications from influenza.

There are special considerations regarding vaccination of persons with history of egg allergy.

What are the influenza vaccine options this season?

There are several flu vaccine options for the 2013-2014 flu season.

Traditional flu vaccines made to protect against three different flu viruses (called “trivalent” vaccines) are available. In addition, this season flu vaccines made to protect against four different flu viruses (called “quadrivalent” vaccines) also are available.

The trivalent flu vaccine protects against two influenza A viruses and an influenza B virus. The following trivalent flu vaccines are available:

The quadrivalent flu vaccine protects against two influenza A viruses and two influenza B viruses. The following quadrivalent flu vaccines are available:

(*”Healthy” indicates persons who do not have an underlying medical condition that predisposes them to influenza complications.)

CDC does not recommend one flu vaccine over the other. The important thing is to get a flu vaccine every year.

Package inserts should be consulted for recommended age groups and possible contraindications for each vaccine in addition to information regarding additional components of various vaccine formulations.

In addition, the Advisory Committee on Immunization Practices (ACIP), Influenza Vaccine Recommendations, 2013-14 should be consulted.

Are any of the available flu vaccines recommended over others?

No. CDC does not recommend one flu vaccine over another. This includes deciding between trivalent or quadrivalent vaccine or between injection (the flu shot) or nasal spray vaccine.

When should vaccination occur?

Flu vaccination should begin soon after vaccine becomes available, ideally 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, most of the time 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.

All children aged 6 months--8 years who are recommended for 2 doses should receive their first dose as soon as possible after vaccine becomes available; these children should receive the second dose at least 4 weeks later. This practice increases the opportunity for both doses to be administered before or shortly after the onset of influenza activity.

To avoid missed opportunities for vaccination, providers should offer vaccination during routine health-care visits or during hospitalizations whenever vaccine is available.

See Vaccine Dose Considerations for Children 6 Months through 8 Years of Age for more information.

Vaccination for Children

Children under 6 months old are the pediatric group at highest risk of influenza complications, but they are too young to get an influenza vaccine. The best way to protect young children is to make sure members of their household and their caregivers are vaccinated.

Influenza vaccination is recommended for all children 6 months of age and older.

Some children 6 months through 8 years of age require 2 doses of influenza vaccine. Children in this age group who are getting vaccinated for the first time will need two doses. Some children who have received influenza vaccine previously will also need two doses. The 2013-2014 ACIP recommendations has an algorithm to help guide clinician decision-making regarding vaccination of children 6 months- 8 years of age.

The 2009 H1N1 virus continues to circulate. It wasn’t added to the seasonal vaccine until the 2010-2011 flu season. This means that children who did not get the 2009 H1N1 vaccine in 2009-2010, or a seasonal flu vaccine in 2010-2011 or later, will not be fully protected from the 2009 H1N1 virus until they receive 2 doses of the 2013-2014 flu vaccine.

2 Dose Vaccination Instructions

The first dose should be given as soon as vaccine becomes available, and the second dose should be given 28 more days after the first dose. The first dose “primes” the immune system; the second dose provides immune protection. Children who only get one dose but need two doses can have reduced or no protection from a single dose of flu vaccine. Two doses are necessary to protect these children. If your patient needs the two doses, begin the process early, so that children are protected before influenza starts circulating in your community. Make sure to remind the parent to follow up to get the child a second dose if they need one. It usually takes about two weeks after the second dose for protection to begin.

Children who require two doses of flu vaccine do not need to receive the same flu vaccine both times; live or inactivated vaccine can be used for either dose. (Within approved indications and recommendations, no preferential recommendation is made for any type or brand of licensed influenza vaccine over another.)

Vaccination for Adults

Everyone 6 months of age and older are recommended to get the flu vaccine, which includes even the healthiest 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 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

People who have had a severe reaction to an influenza vaccination, and children younger than 6 months of age should not be vaccinated.

People who are moderately or severely ill with or without fever should usually wait until they recover before getting flu vaccine.

A history of Guillain-Barré Syndrome (GBS) within 6 weeks following receipt of influenza vaccine is a precaution for the use of influenza vaccine. Such individuals have a risk of recurrence of GBS with subsequent vaccination, and if not at high risk of severe influenza complications should generally not be vaccinated. However, while data are limited, the established benefits of influenza vaccination might outweigh the risks for many people who have a history of GBS and who also are at high risk for severe complications from influenza.

See Contraindications and Precautions (Table 2) for more information.

Vaccination of People with a History of Egg Allergy

This season, vaccine options are available for the following:

  • Persons with a history of egg allergy who have experienced only hives after exposure to egg
  • Persons with a history of severe reaction to egg
  • Persons with no known history of exposure to egg, but who are suspected of being egg-allergic

All vaccines should be administered in settings in which personnel and equipment for rapid recognition and treatment of anaphylaxis are available.

A previous severe allergic reaction to influenza vaccine, regardless of the component suspected to be responsible for the reaction, is a contraindication to future receipt of the vaccine.

See Influenza Vaccination of Persons with a History of Egg Allergy for complete information and an algorithm to guide decision-making.

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.
  • Live-attenuated influenza vaccine should not be administered until 48 hours after cessation of influenza antiviral therapy.
  • If influenza antiviral medications are administered within 2 weeks after receipt of live-attenuated influenza vaccine, the vaccine dose should be repeated 48 or more hours after the last dose of antiviral medication.
  • Persons receiving antiviral drugs within the period 2 days before to 14 days after vaccination with live-attenuated influenza vaccine should be revaccinated at a later date with any approved vaccine formulation.

Concurrent Administration of Influenza Vaccine With Other Vaccines

  • Inactivated vaccines do not interfere with the immune response to other inactivated vaccines or to live vaccines.
  • Inactivated or live vaccines can be administered simultaneously with live-attenuated influenza vaccine.
  • However, after administration of a live vaccine, at least 4 weeks should pass before another live vaccine is administered.

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