Flu Vaccine

All influenza vaccine formulations will be quadrivalent for the 2021-22 season

Egg-based influenza vaccine licensed in the U.S. will contain hemagglutinin (HA) derived from an A/Victoria/2570/2019 (H1N1) pdm09-like virus, an A/Cambodia/e0826360/2020 (H3N2)-like virus, a B/Washington/02/2019 (B Victoria lineage)-like virus, and a B/Phuket/3073/2013 (B Yamagata lineage)-like virus.

Cell- or recombinant-based influenza vaccines will contain an A/Wisconsin/588/2019 (H1N1) pdm09-like virus, an A/Cambodia/e0826360/2020 (H3N2)-like virus, a B/Washington/02/2019 (B Victoria lineage)-like virus, and a B/Phuket/3073/2013-like (Yamagata lineage) virus. 

What ACIP Recommends

Routine annual influenza vaccination is recommended for all persons aged 6 months or older who do not have contraindications.  A licensed and age-appropriate vaccine formulation should be used for each recipient. 

The Morbidity and Mortality Weekly Report published on August 27, 2021 provides guidance from the Advisory Committee on Immunization Practices (ACIP) for using this year’s flu vaccine products. View all available products on this printable listing of influenza vaccine products available for the 2021-22 season. Access the 2021-22 State Supplied Childhood Flu Vaccines At-A-Glance chart  for formulations available to Washington State Childhood Vaccine providers.

Dosing for Children Aged 6 Months to 8* Years OlD

Influenza vaccine dosing algorithm for children 6 months through 8 years* -Advisory Committee on Immunization Practices, United States, 2021-22 influenza season  8 and under chart

*For children aged 8 years who require 2 doses of vaccine, both doses should be administered even if the child turns age 9 years between receipt of doses 1 and 2

Thimerosal in Flu Vaccine

Thimerosal is used as a preservative in all multi-dose vial presentations of influenza vaccine. A 0.5 milliliter (mL) dose drawn from a multi-dose vial contains up to 25 micrograms thimerosal, depending on the manufacturer. Single-dose flu vaccine presentations-prefilled syringe, single-dose vial, and single-use nasal spray-are thimerosal-free.

In Washington State, according to RCW 70A.230.120, "a person who is known to be pregnant or who is under three years of age shall not be vaccinated with a mercury-containing vaccine or injected with a mercury-containing product that contains more than 0.5 micrograms of mercury per 0.5 milliliter dose."

Expiration Dates for Multi-Dose Vials

Trade Name
Vaccine expires 28 days after the multi-dose vial is opened or accessed (needle-punctured)
Vaccine is usable through the expiration date on the multi-dose vial label whether or not it has been opened or accessed
Seqirus Afluria
Seqirus Flucelvax  
Sanofi Pasteur Fluzone