Advisory Committee on Immunization Practices Issues Recommendations for 2021-22 Influenza Season

The Advisory Committee on Immunization Practices (ACIP) has issued its recommendations for the 2021-22 influenza season. As Grohskopf, et al. (2021) state, "Routine annual influenza vaccination of all persons aged ≥6 months who do not have contraindications continues to be recommended." They emphasize, "Vaccination provides important protection from influenza illness and its potential complications."

Updated information in this report issued in MMWR today includes the following:

1. All seasonal influenza vaccines expected to be available for the 2021–22 season are quadrivalent, containing hemagglutinin (HA) derived from one influenza A(H1N1)pdm09 virus, one influenza A(H3N2) virus, one influenza B/Victoria lineage virus, and one influenza B/Yamagata lineage virus.

2. The composition of the 2021–22 U.S. seasonal influenza vaccines includes updates to the influenza A(H1N1)pdm09 and influenza A(H3N2) components. For the 2021–22 season, U.S.-licensed influenza vaccines will contain an influenza A/Victoria/2570/2019 (H1N1)pdm09-like virus (for egg-based vaccines) or an influenza A/Wisconsin/588/2019 (H1N1)pdm09-like virus (for cell culture–based and recombinant vaccines); an influenza A/Cambodia/e0826360/2020 (H3N2)-like virus; an influenza B/Washington/02/2019 (Victoria lineage)-like virus; and an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus.

3. One labeling change is described. In March 2021, FDA granted approval for the use of Flucelvax Quadrivalent (cell culture–based quadrivalent inactivated influenza vaccine [ccIIV4]) for children aged 2 through <4 years. Flucelvax Quadrivalent had previously been approved for persons aged ≥4 years; approval for those aged 4 through <18 years was based on immunogenicity data and required a postmarketing efficacy study. The new approval is based on a randomized observer-blinded clinical efficacy study conducted among children aged 2 through <18 years over three seasons, in which Flucelvax Quadrivalent demonstrated efficacy against laboratory-confirmed influenza of 54.6%(95% confidence interval [CI] = 45.7%–62.1%) compared with a noninfluenza control vaccine. Flucelvax Quadrivalent is now approved for persons aged ≥2 years (21).

4. Guidance regarding administration of influenza vaccines with other vaccines has been updated to reflect consideration for COVID-19 vaccination, which is expected to continue in the United States before and during the 2021–22 influenza season. Current guidance for the use of COVID-19 vaccines indicates that these vaccines can be co-administered with other vaccines, including influenza vaccines. Providers should consult current COVID-19 vaccine recommendations and guidance for up-to-date information. ACIP recommendations for the use of COVID-19 vaccines are available at: Interim clinical guidance for the use of COVID-19 vaccines is available at These pages should be checked periodically for updated information.

5. Guidance concerning timing of vaccination has been modified. For women in the third trimester of pregnancy, vaccination soon after vaccine becomes available can now be considered. As in previous seasons, children who need 2 doses of influenza vaccine administered ≥4 weeks apart (those aged 6 months through 8 years who have never received influenza vaccine or who have not previously received a lifetime total of ≥2 doses) are recommended to receive the first dose as soon as possible after vaccine becomes available. For nonpregnant adults, early vaccination (i.e., in July and August) should be avoided unless there is concern that later vaccination might not be possible.

6. Contraindications and precautions to the use of ccIIV4 and RIV4 have been modified, specifically with regard to persons with a history of severe allergic reaction (e.g., anaphylaxis) to an influenza vaccine. A history of a severe allergic reaction (e.g., anaphylaxis) to a previous dose of any egg-based IIV, LAIV, or RIV of any valency is a precaution to use of ccIIV4. A history of a severe allergic reaction (e.g., anaphylaxis) to a previous dose of any egg-based IIV, ccIIV, or LAIV of any valency is a precaution to use of RIV4. Use of ccIIV4 and RIV4 in such instances should occur in an inpatient or outpatient medical setting under supervision of a provider who can recognize and manage a severe allergic reaction; providers can also consider consulting with an allergist to help identify the vaccine component responsible for the reaction. For ccIIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any ccIIV of any valency or any of component of ccIIV4 is a contraindication to future use of ccIIV4. For RIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any RIV of any valency or any component of RIV4 is a contraindication to future use of RIV4.

Reference: Grohskopf LA, et al. Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices, United States, 2021–22 Influenza Season. Morbidity and Mortality Weekly Report. Vol. 70, No. 5. Aug. 27, 2021.