Flu Vaccine Recommendations Updated by CDC

Troy Brown, RN

August 22, 2019

The Advisory Committee on Immunization Practices (ACIP) continues to recommend routine yearly influenza vaccination for everyone aged 6 months or older who has no contraindications, according to updated recommendations for the 2019–2020 influenza season.

The recommendations were published online today in Morbidity and Mortality Weekly Report. The updates follow ACIP meetings on October 25, 2018, February 27, 2019, and June 27, 2019.

Clinicians should offer vaccination by the end of October, according to the authors, and preferably before influenza activity begins in the community. Vaccination efforts should continue for the duration of the influenza season.

Children aged 6 months through 8 years who need two doses should get their first dose at the earliest opportunity so they can receive the second dose, which must be given at least 4 weeks later, by the end of October.

For those who only need one dose for the season, vaccinating as early as July and August may result in less than optimal immunity before the season ends, especially among older adults.

For the 2019–2020 season, ACIP expects inactivated influenza vaccines (IIVs), recombinant influenza vaccine (RIV), and live attenuated influenza vaccine (LAIV) to be available. "Standard-dose, unadjuvanted, inactivated influenza vaccines will be available in quadrivalent formulations (IIV4s). High-dose (HD-IIV3) and adjuvanted (aIIV3) inactivated influenza vaccines will be available in trivalent formulations. Recombinant (RIV4) and live attenuated influenza vaccine (LAIV4; intranasal vaccine) will be available in quadrivalent formulations," ACIP explains in the recommendations.

Individuals with egg allergy or previous reaction to eggs may receive any licensed, recommended influenza vaccine (IIV, RIV4, or LAIV4).

High-Risk Populations

Individuals with increased risk for severe illness or complications from influenza should be vaccinated. These include children aged 6 through 59 months; those aged 50 years or older; adults and children with chronic disease; immunocompromised individuals; women who are or who expect to be pregnant during influenza season; children and adolescents aged 6 months through 18 years who may have a higher risk for Reye syndrome after influenza virus infection because they are taking aspirin- or salicylate-containing medications; those who live in long-term care facilities; American Indians/Alaska Natives; and those who are extremely obese (body mass index ≥40 for adults).

Persons in all risk groups can receive an age-appropriate dose of IIV or RIV4. However, the authors recommend against the LAIV4 for certain populations, including pregnant women and some of the above high-risk groups. The recommendations include a table with contraindications and precautions for the LAIV.

Immunocompromised individuals should be given an age-appropriate IIV or RIV4. LAIV4 is not recommended, as there is an "uncertain but biologically plausible risk" for illness associated with the vaccine.

Individuals who live with or who care for high-risk individuals — such as healthcare workers or those who work in a nonmedical capacity in healthcare facilities — should also be vaccinated.

Having a history of Guillain-Barré syndrome within 6 weeks of receiving any type of influenza immunization "is considered a precaution to vaccination."

ACIP does not recommend one vaccine preferentially for those for whom there is "more than one licensed, recommended, and appropriate product available."

Updated Influenza Vaccine Strains

For the 2019–2020 season, trivalent influenza vaccines will contain hemagglutinin (HA) from an A/Brisbane/02/2018 (H1N1)pdm09-like virus, an A/Kansas/14/2017 (H3N2)–like virus, and a B/Colorado/06/2017–like virus (Victoria lineage).

In addition to HA derived from the three viruses in trivalent vaccines, quadrivalent vaccines will contain a second influenza B vaccine virus — a B/Phuket/3073/2013–like virus (Yamagata lineage).

"This composition includes updates in the influenza A(H1N1)pdm09 and influenza A(H3N2) components of the vaccine," ACIP says.

Regulatory Actions

Last October, the US Food and Drug Administration (FDA) approved a wider age indication for Afluria Quadrivalent (IIV4) (Seqirus); the vaccine, which was previously licensed for children aged 5 years or older, can now be given to those aged 6 months or older.

Children aged 6 through 35 months will receive a smaller dose (0.25 mL per dose, containing 7.5 µg of HA per vaccine virus) than those aged 36 months and older (0.5 mL per dose, containing 15 μg of HA per vaccine virus).

In January, the FDA approved a changed dose volume for Fluzone Quadrivalent (IIV4) (Sanofi Flu) for children aged 6 through 35 months: the previous recommendation was 0.25 mL (containing 7.5 µg of HA per vaccine virus). Children in that age range may now either continue taking 0.25 mL (containing 7.5 µg of HA per vaccine virus) or increase the dosage to 0.5 mL (containing 15 µg of HA per vaccine virus). Children aged 36 months or older and adults should receive 0.5 mL per dose.

Additional information, including updates, can be found at CDC's influenza website.

The authors have disclosed no relevant financial relationships.

MMWR. Published online August 22, 2019. ACIP recommendations

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