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IAC Express: Weekly immunization news and information

Issue 1388: October 9, 2018

Ask the Experts: CDC Experts Answer Your Questions

As a thank-you to our loyal IAC Express readers, we periodically publish extra editions such as this one, with new and updated "Ask the Experts" Q&As answered by CDC experts. 

IAC extends thanks to our experts: Andrew T. Kroger, MD, MPH; Candice L. Robinson, MD, MPH; Raymond A. Strikas, MD, MPH, FACP, FIDSA; Tina S. Objio, MSN, MHA, RN; and JoEllen Wolicki, BSN, RN, all from the National Center for Immunization and Respiratory Diseases, CDC.

Influenza Vaccines

Influenza Vaccines

Q: What's new in the 2018–19 influenza vaccine recommendations?

A: The 2018–19 ACIP influenza vaccine recommendations were published on August 24, 2018, and are available at The new guidance:

  • describes the vaccine composition for this season (a change in the H3N2 and B [Victoria] components);
  • discusses recent FDA labeling changes, including expansion of the age indication for Afluria Quadrivalent (Seqirus) to 5 years and older (previously licensed for persons 18 years and older) and Fluarix Quadrivalent (GSK) to age 6 months and older (previously licensed for persons 3 years and older);
  • recommends that live attenuated influenza vaccine (LAIV, FluMist; AstraZeneca) may be used when age- and health condition-appropriate; and
  • recommends that persons with a history of egg allergy of any severity may receive any recommended and age-appropriate influenza vaccine (inactivated influenza vaccine [IIV], recombinant influenza vaccine [RIV], or LAIV).

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Q: Which influenza vaccines will be available during the 2018–2019 influenza season?

A: Multiple manufacturers are producing influenza vaccine for the U.S. market for the 2018–2019 season. Inactivated vaccines will be produced using egg-based, cell culture–based and recombinant technologies. Most inactivated influenza vaccines will be quadrivalent (containing four strains of influenza virus) rather than trivalent (three strains). ACIP does not state a preference for one influenza vaccine over another for persons for whom more than one vaccine is recommended and age and health condition appropriate. A complete listing of influenza vaccine products is available from the Immunization Action Coalition (IAC) at

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Q: What are the differences between trivalent and quadrivalent influenza vaccines?

A: Influenza vaccine produced for the current season will be either trivalent (three components) or quadrivalent (4 components). Both types of vaccine contain two A viruses and one B virus: The components of the 2018–19 vaccines are:

  • A/Michigan/45/2015 (H1N1) pdm09-like virus,
  • A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus (new for the 2018–19 season),
  • B/Colorado/06/2017–like virus (Victoria lineage) (new for the 2018–19 season).

The quadrivalent vaccine will contain these three viruses, plus a B/Phuket/3073/2013–like virus (Yamagata lineage) virus.

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Q: If quadrivalent vaccine includes one additional strain, why isn't it preferred for use over trivalent vaccine?

A: Two different types of influenza B virus are likely to cause disease during an influenza season, but trivalent influenza vaccines contain only one type of influenza B virus. The quadrivalent vaccine includes both types of B virus. Not all types of vaccine are likely to be uniformly available in any practice setting or locality. Consequently, ACIP does not express a preference for use of one type of influenza vaccine over another type (that is, quadrivalent over trivalent) for those for whom more than one type of vaccine is indicated and available. Vaccination should not be delayed in order to obtain a specific product when an appropriate one is already available.

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Q: Which formulations of influenza vaccines (i.e., nasal spray, injectable high-dose, and injectable standard-dose) are licensed for various age groups?

A: There are multiple manufacturers of influenza vaccine and each may have differences in their product line (for example, licensed age group). ACIP does not state a preference for one influenza vaccine over another for persons for whom more than one vaccine is recommended and age and health condition appropriate. IAC has developed a handout that summarizes each of the products available for the current influenza vaccination season that is available online at

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Q: We are having trouble getting a supply of Fluzone Intradermal (Sanofi Pasteur). Is there a shortage of this vaccine?

A: As of the 2018–19 influenza season, Sanofi Pasteur is no longer distributing Fluzone Intradermal in the United States.

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Q: We have noticed that ACIP recommends that we begin vaccinating with seasonal influenza vaccine in September or even earlier. Does protection from seasonal influenza vaccine decline or wane within 3 or 4 months of vaccination? Should I wait until later in the year to vaccinate my elderly or medically frail patients?

A: No one can predict when influenza disease will peak in a given season. Several studies have reported decreases in vaccine effectiveness within a single influenza season with increasing time since vaccination. However, waning effects have not been observed consistently across age groups, virus subtypes, and seasons. While delaying vaccination might permit greater immunity later in the season, deferral could result in missed opportunities to vaccinate, as well as difficulties in vaccinating a large number of people within a more limited time period. Vaccination programs should balance maximizing the likelihood of persistence of vaccine-induced protection through the season with avoiding missed opportunities to vaccinate or vaccinating after influenza virus circulation begins.
For people who have already been fully vaccinated, revaccination later in the season is not recommended.

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Q: Which influenza vaccines can we give to children?

A: Among the injectable inactivated influenza vaccines, only Fluzone (Sanofi Pasteur), FluLaval (GSK), and Fluarix (GSK) are approved by the FDA for use in children ages 6 through 35 months. There are several inactivated influenza vaccines that can be given to children age 3 years or older.
The nasal spray live attenuated influenza vaccine (LAIV, FluMist, AstraZeneca) is approved for healthy children age 2 years and older. Information about all influenza vaccines available in the U.S. is available in IAC's handout titled "Influenza Vaccine Products for the 2018–2019 Influenza Season" at

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Q:  Please provide details about the use of FluLaval and Fluarix influenza vaccine in children younger than 3 years.

A: On November 18, 2016, the FDA approved an extension of the age range of FluLaval Quadrivalent IIV to include children 6 through 35 months of age. FluLaval was previously approved for people 3 years of age and older. The approval of the extended age range for FluLaval was based on a study showing an equivalent ("non-inferior") response compared to children who received the Fluzone pediatric dosage. The vaccine will be supplied in manufacturer-filled syringes and multi-dose vials. The dosage approved for children 6 through 35 months of age is 0.5 mL—the same dosage as for people 3 years of age and older.
On January 11, 2018, the FDA approved an extension of the age range of Fluarix Quadrivalent IIV to include children 6 through 35 months of age. Fluarix was previously approved for people 3 years of age and older. The approval of the extended age range for Fluarix was based on a study that demonstrated protection from influenza virus infection and reduced influenza-associated complications compared to a non-influenza vaccine. The vaccine is supplied in manufacturer-filled syringes. The dosage approved for children 6 through 35 months of age is 0.5 mL—the same dosage as for people 3 years of age and older.
Fluzone is the only influenza vaccine with a dosage of 0.25 mL for children age 6 through 35 months.

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Q:  Which children younger than age 9 years will need 2 doses of influenza vaccine in this influenza season?

A: Children age 6 months through 8 years should receive a second dose 4 weeks or more after the first dose 1) if they are receiving influenza vaccine for the first time, 2) if they did not receive a total of at least two doses of trivalent or quadrivalent influenza vaccine before July 1 of the current year, or 3) if their vaccination history is unknown. The two doses need not have been received during the same season or consecutive seasons. IAC's handout titled "Guide for Determining the Number of Doses of Influenza Vaccine to Give to Children Ages 6 Months Through 8 Years" provides guidance on this issue; it is available at

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Q:  Can a child 6 through 35 months of age who needs 2 doses of influenza vaccine this season receive a combination of Fluzone, FluLaval, or Fluarix vaccine?

A: Yes. Fluzone (0.25 mL dose), FluLaval (0.5 mL dose), and Fluarix (0.5 mL dose) are approved by the FDA for use in children 6 through 35 months of age. If a child is age 2 years or older, FluMist may also be used when health condition appropriate.

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Q:  If a child receives Fluzone vaccine (0.25 mL) at age 34 or 35 months for the first time and then returns for the second dose at age 37 months, should we give another 0.25 mL dose of Fluzone or should we give the 0.5 mL dose that is indicated for ages 3 and older?

A: The child should always receive the dose appropriate for his or her age at the time of the clinic visit; at age 37 months that would be 0.5 mL.

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Q:  Is influenza vaccine recommended for pregnant women?

A: Yes. It is especially important to vaccinate pregnant women because of their increased risk for influenza-related complications. An increased risk of severe influenza infection was also observed in postpartum women (those who delivered within the previous 2 weeks) during the 2009–10 H1N1 pandemic. Vaccination can occur in any trimester, including the first. Only inactivated vaccine should be given to pregnant women.

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Q:  I have a patient who is now 12 weeks pregnant. She received a dose of quadrivalent inactivated influenza vaccine earlier this season, before she was pregnant. Should we give her another dose of this year’s influenza vaccine since she was not pregnant at the time of her first dose?

A: The Advisory Committee on Immunization Practices (ACIP) does not recommend more than one dose of influenza vaccine per season, except for certain children being vaccinated for the first time.

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Q:  Please tell me about Fluad, one of the influenza vaccines for people age 65 years and older.

A: In November 2015, FDA licensed Fluad (Seqirus), a trivalent, MF59-adjuvanted inactivated influenza vaccine, for people age 65 years and older. Fluad is the first adjuvanted influenza vaccine marketed in the U.S. An adjuvant is a substance added to a vaccine to increase its immunogenicity. The MF59 adjuvant is based on squalene, an oil that occurs naturally in many plants and animals. Fluad has been used in Europe since 1997 and is approved in 38 other countries. In contrast to Fluzone High-Dose (Sanofi Pasteur), Fluad is a standard-dose vaccine, containing 15 mcg of hemagglutinin per virus per dose (total of 45 mcg). In a small observational study among adults age 65 years and older, Fluad was about 63% more effective than unadjuvanted trivalent IIV. ACIP has not stated a preference for Fluad (or Fluzone HD) over standard dose IIV for people age 65 years and older.

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Q:  Sometimes patients age 65 years and older who have received the standard-dose influenza vaccine hear about the high-dose (Fluzone High-Dose) or adjuvanted vaccine (Fluad) and want to receive that, too. Is this okay to administer?

A: No. ACIP does not recommend that anyone receive more than one dose of influenza vaccine in a season, except for certain children age 6 months through 8 years for whom two doses are recommended.

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Q:  Which healthcare personnel should be vaccinated against influenza?

A: It is important to vaccinate ALL hospital and outpatient-care personnel, especially those that have direct contact with patients. In addition to physicians and nurses, vaccination in a hospital setting also includes full-time and part-time employees in radiology, laboratories, pharmacy, human resources, facilities management (housekeeping), food services, or laundry. Vaccinate volunteers as well. Others who should be vaccinated are emergency response workers, employees of nursing homes and assisted living programs, and providers of home care.

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Q:  What is the preferred anatomic site for administration of inactivated influenza vaccine (IIV) and recombinant influenza vaccine?

A: IIV should be administered in the anterolateral thigh muscle of an infant or young child. IIV and RIV (for persons age 18 years and older) should be administered in the deltoid muscle of an older child, adolescent, or adult. The anterolateral thigh muscle can also be used for an older child, adolescent, or adult if necessary. It is critical that intramuscular influenza vaccine be injected into a muscle. Influenza vaccination season is an opportune time to review proper intramuscular injection techniques with your staff. IAC has prepared a handout on how to administer intramuscular vaccine injections (available at that can be used as a staff training tool.

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Q:  For whom is inactivated influenza vaccine contraindicated?

A: Persons who have experienced a severe allergic reaction to a prior dose of influenza vaccine, or who are known to have a severe allergy to a vaccine component (except egg) should not be vaccinated.
Precautions to vaccination include moderate or severe acute illness, and history of Guillain-Barré syndrome within 6 weeks of a dose of influenza vaccine.

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Q:  What are the contraindications for live attenuated influenza vaccine (LAIV)?

A: Contraindications to LAIV are:

  • history of a severe allergic reaction to a vaccine component (except egg—see next question) or after a previous dose of any influenza vaccine;
  • concomitant aspirin- or salicylate-containing therapy in children and adolescents because of the risk of Reye syndrome;
  • children age 2 through 4 years who have received a diagnosis of asthma or whose parents or caregivers report that a healthcare provider has told them during the preceding 12 months that their child had wheezing or asthma or whose medical record indicates a wheezing episode during the preceding 12 months;
  • immunosuppression due to any cause, including medications or HIV infection;
  • close contacts and caregivers of severely immunosuppressed persons who require a protected environment (e.g. reverse isolation in a hospital);
  • pregnancy;
  • receipt of influenza antiviral medication within the previous 48 hours. 

Precautions to LAIV are:

  • moderate or severe acute illness with or without fever;
  • history of Guillain-Barré syndrome within 6 weeks of receipt of influenza vaccine;
  • asthma in a person age 5 years or older;
  • underlying medical conditions that might predispose to complications after influenza virus infection, such as chronic pulmonary, cardiovascular (except isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders including diabetes mellitus.

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Q:  What is the latest ACIP guidance on influenza vaccination and egg allergy?

A: ACIP recommends that people with a history of egg allergy who have experienced only hives after exposure to egg should receive influenza vaccine without specific precautions (except a 15-minute observation period for syncope). Any age-appropriate vaccine (IIV, RIV or LAIV) may be used. People who report having had an anaphylactic reaction to egg (more severe than hives) may also receive any age-appropriate influenza vaccine (IIV, RIV or LAIV). The vaccine for those individuals should be administered in a medical setting (such as a physician office or health department clinic). Vaccine administration should be supervised by a healthcare provider who is able to recognize and manage severe allergic conditions. Although not specifically recommended by ACIP, providers may prefer an egg-free recombinant vaccine (Flublok; Sanofi Pasteur) for people age 18 years and older with severe egg allergy.
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. For a complete list of vaccine components (i.e., excipients and culture media) used in the production of the vaccine, check the package insert (at or go to
For more details about giving influenza vaccine to people with a history of egg allergy, see, pages 9–10. You also may find the IAC handout "Influenza Vaccination of People with a History of Egg Allergy" helpful (see

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Q:  Is there any plan to change the Influenza Vaccine Information Statement (VIS) for the 2018–19 influenza season?

A: The current influenza vaccine VIS (dated August 7, 2015) may be used for the 2018–19 influenza season. No changes are planned.

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Q:  When administering influenza vaccine, is giving patients a VIS mandatory or is it only "recommended"?

A: Giving patients an influenza Vaccine Information Statement (VIS) is mandatory under the National Childhood Vaccine Injury Act of 1986. The VIS must be given to all adults as well as to parents or guardians of children prior to vaccination. Two VISs are available, one for live attenuated influenza vaccine (LAIV) and one for inactivated influenza vaccine (IIV). Each can be found at, along with many translations.

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How to submit a question to Ask the Experts

IAC works with CDC to compile new Ask the Experts Q&As for our publications based on commonly asked questions. We also consider the need to provide information about new vaccines and recommendations. Most of the questions are thus a composite of several inquiries.

You can email your question about vaccines or immunization to IAC at

As we receive hundreds of emails each month, we cannot promise that we will print your specific question in our Ask the Experts feature. However, you will get an answer.

You can also email CDC's immunization experts directly at There is no charge for this service.

If you have a question about IAC materials or services, email

Please forward these Ask the Experts Q&As to your colleagues and ask them to subscribe to IAC Express.

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