What are the components of the 2020-2021 Northern Hemisphere seasonal influenza vaccines?

Updated: Aug 07, 2020
  • Author: Hien H Nguyen, MD, MS; Chief Editor: Michael Stuart Bronze, MD  more...
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The vaccine viral strains recommended by the World Health Organization and the Centers for Disease Control and Prevention (CDC) for the 2020-2021 Northern Hemisphere influenza season differ from those from the previous influenza season. Additionally, the specific composition also differs between vaccines that are manufactured using an egg-based culture from those utilizing recombinant or cell culture technologies. [8]

The egg-based vaccines for the 2020-2021 Northern Hemisphere vaccine season contain the following components:

  • A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09–like virus (new for 2020-2021)
  • A/Hong Kong/2671/2019 (H3N2)–like virus (new for 2020-2021)
  • B/Washington/02/2019 (B/Victoria lineage)–like virus (new for 2020-2021)

The quadrivalent egg-culture influenza vaccines contain an additional B strain, B/Phuket/3073/2013-like virus (B/Yamagata lineage) (no change from prior season), in addition to the 3 viral strains listed above.

The recombinant or cell-culture quadrivalent vaccine composition is as follows:

  • A/Hawaii/70/2019 (H1N1)pdm09–like virus (new for 2020-2021)
  • A/Hong Kong/45/2019 (H3N2)–like virus (new for 2020-2021)
  • B/Washington/02/2019 (B/Victoria lineage)–like virus (new for 2020-2021)
  • B/Phuket/3073/2013–like (Yamagata lineage) virus (no change from the prior season)

Injectable vaccine, which contains inactivated virus, is available in a variety of dosage forms. The intramuscular (IM) form contains 45 µg of influenza hemagglutinin per 0.5 mL. A microinjection system for intradermal delivery (Fluzone Intradermal) is available in the United States and features an ultrafine needle that is 90% shorter than the typical 1- to 1.5-inch needle used for IM injections. The intradermal dosage form contains 27 µg of influenza hemagglutinin per 0.1 mL. The recombinant influenza vaccine (Flublok Quadrivalent) and the cell-cultured vaccine (Flucelvax Quadrivalent) contain no egg proteins, antibiotics, or preservatives. [9] Adults aged 65 years or older may receive a high-dose inactivated influenza vaccine (Fluzone High-Dose). [49]

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