What’s New About This Year’s Flu Shot – and Why 

Shandra Martinez

| 3 min read

Close up shot of healthcare worker injecting black female patient with COVID-19 vaccine. The woman is wearing a face mask and looking in the opposite direction of the needle.
It’s time to roll up our sleeves for this year’s seasonal flu shot. Flu shots and nasal mists are being offered to adults and children age 6 months old and up at regular checkup appointments and at health clinics and pharmacies.
Health care providers hope to get lots of people vaccinated against the flu before the virus typically takes hold in the colder months, causing fevers, body aches and chills. Each year, the flu vaccines and flu mists are customized to best fit the dominant strains of the flu virus that are circulating. Let’s look at what’s new about this year’s flu shot – and why.

Why do we need a flu shot every year?

The composition of flu vaccines in the United States changes each year. This is because there are lots of different strains of flu virus. Flu shots are updated annually to try to offer the best protection possible against the strains of influenza viruses that researchers believe will be the most common ones to spread among the population this season. 
All flu vaccines for the 2022-2023 season will be quadrivalent (four component), according to the Centers for Disease Control and Prevention (CDC). Most will be thimerosal-free or thimerosal-reduced vaccine (93%), and about 20% of flu vaccines will be egg-free.
Here are this year’s egg-based, cell-based and recombinant flu vaccines, per the CDC:
Egg-based vaccine composition recommendations:
  • A/Victoria/2570/2019 (H1N1) pdm09-like virus
  • A/Darwin/9/2021 (H3N2)-like virus (updated)
  • B/Austria/1359417/2021-like virus (B/Victoria lineage) (updated)
  • B/Phuket/3073/2013-like virus (B/Yamagata lineage)
Cell culture- or recombinant-based vaccine composition recommendations:
  • A/Wisconsin/588/2019 (H1N1) pdm09-like virus
  • A/Darwin/6/2021 (H3N2)-like virus (updated)
  • B/Austria/1359417/2021-like virus (B/Victoria lineage) (updated)
  • B/Phuket/3073/2013-like virus (B/Yamagata lineage)
While these virus strain ingredients may look like alphabet soup to non-scientists, the recommendations are important to have so the vaccines are manufactured according to one set of guidelines. All flu vaccines meet FDA safety and effectiveness requirements.

What are the different types of flu vaccines?

Once a person is vaccinated, it takes the body about two weeks to develop antibodies to these virus strains, offering them protection against the different types of influenza viruses. There are two main types of flu vaccines:
  • The flu shot: the most common type of flu shot is injected into the arm and includes an inactivated – or dead – form of the influenza virus.
  • Nasal spray flu mist: this is injected into the nose and includes a live but weakened form of the influenza virus. Flu mist is approved for people age 2 to 49 years old.

How are flu vaccines made?

Not all influenza vaccines are created in the same way. Here’s a simple primer on the different methods, according to the CDC:
  • Egg-based flu vaccines. This is the most common type of vaccine. It’s used to make both the common flu shots, and the newer nasal spray flu vaccines. The viruses are injected into and incubated in hen’s eggs before being harvested to make the vaccines.
  • Cell-based flu vaccines. This type of production has been used the last several years and involves viruses being grown in animal cells in a laboratory setting, then being harvested for use in flu shots.
  • Recombinant flu vaccines. These vaccines are created synthetically using genetic technology. They make a type of antigen that triggers the human body to create antibodies that target specific types of influenza viruses.
Talk with your health care provider about which type of flu vaccine is right for you. Pharmacies and health care providers are offering the flu vaccine now.
Learn more about the flu by visiting bcbsm.com/preventflu.
Photo credit: Getty Images

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