Update: 2021-2022 Flu Season

Drug Topics JournalDrug Topics December 2021
Volume 165
Issue 12

Influenza is expected to make a comeback this year, and no one knows how severe it may be.

Thanks to COVID-19 infection-control measures, influenza activity was low last year. However, as restrictions ease and lockdowns end, the flu is poised

for a comeback. To help mitigate a surge in cases, the CDC has issued revised flu guidelines1 for the 2021-2022 flu season.

Updated Flu Vaccine Composition

Every year, the FDA Vaccines and Related Biological Products Advisory Committee recommends an updated flu vaccine composition for flu vaccines in the United States.2 This season, all flu vaccines will protect against the 4 viruses expected to be most common. There are 2 updates this season compared with last season1 for influenza A (H1N1) and influenza A (H3N2) vaccine virus components.

All Flu Vaccines Will Be Quadrivalent

A quadrivalent flu vaccine3 protects patients against 4 different flu viruses: 2 influenza A and 2 influenza B viruses. In previous years, flu vaccines protected against 2 influenza A and 1 influenza B virus. Adding another protection against influenza B provides broader coverage against flu viruses.

Flucelvax Quadrivalent Now Approved in Individuals 6 Months and Older

Patients aged 6 months to 8 years receive either 1 or 2 doses; for patients who need 2 doses—a decision dependent on vaccination history—doses should be spaced apart by at least 4 weeks. Patients 9 years and older will receive 1 dose.4

Flu and COVID-19 Vaccines Can Be Coadministered

Pharmacists can feel comfortable recommending and/or administering the flu vaccine at the same time as the COVID-19 vaccine. According to the CDC, “Experimental evidence and extensive clinical experience provide the scientific basis for administering vaccines simultaneously. Simultaneously administering all vaccines for which a person is eligible at the time of a visit increases the probability that a child, adolescent, or adult will be vaccinated fully by the appropriate age.”5

When administering the flu and COVID-19 vaccines together, patients should be injected in separate sites—1 vaccine in each arm. If both vaccines must be given in the same arm, the injection site should be separated by at least 1 inch. Documentation should reflect vaccine injection-site locations in case of any reactions.6

More Guidance About Vaccine Timing for Some Groups

  • By now (December), everyone should, ideally, be vaccinated. The CDC recommends vaccination by the end of October; however, patients who have not been vaccinated by the end of October should still get vaccinated because the flu usually peaks in February and can last until May. The CDC now generally recommends the following1:
  • Adults should not get vaccinated early (in July or August) because protection decreases over time. However, if a patient is unable to return at a later date, early vaccination may be appropriate.
  • Children should be vaccinated as soon as the vaccine is available, as early as July or August. This helps space the second dose, if needed, at least 4 weeks after the first dose. • Women in the third trimester of pregnancy may be appropriate candidates for early vaccination.

Updated Contraindications, Precautions for Flucelvax Quadrivalent and Flublok Quadrivalent

If a patient has a history of severe allergic reaction to any flu vaccine, this is now considered a precaution—not a contraindication—for administering the Flucelvax Quadrivalent or Flublok Quadrivalent vaccine. In these patients, vaccination should take place in a medical setting under the supervision of a health care professional who can manage a severe allergic reaction.7

For Flucelvax Quadrivalent, a history of severe allergic reaction to any Flucelvax vaccine is a contraindication to future use of Flucelvax Quadrivalent. For Flublok Quadrivalent, a history of severe allergic reaction to any Flublok vaccine is a contraindication to future use of Flublok Quadrivalent.7

The 2021-2022 Flu Season: What to Expect

For more information about the 2021-2022 flu season and flu vaccines, Drug Topics® talked with Gregg Sylvester, MD, MPH, chief medical officer of Seqirus, the company that manufactures Flucelvax Quadrivalent. Although last year’s flu season was comparatively “light,” Sylvester cautioned that that does not necessarily mean this year will be light too. “Although recent data show that this season is starting low, the flu is coming back,” he said.

“We don’t know if it will be mild, moderate, or severe. What we do know is that every year we need to vaccinate everyone who is eligible.” Sylvester noted that many of the precautionary measures for COVID-19, such as mask wearing, hand washing, quarantining, and social distancing, were originally developed for pandemic flu. These measures are helpful for the flu and COVID-19 because both are respiratory viruses and, therefore, will help lower rates of both. “However,” he added, “when we start to congregate and stop wearing masks, various respiratory viruses will spread again.”

Sylvester also encouraged pharmacists to coadminister flu and COVID-19 vaccines to patients when possible. “As a pediatrician, we say, ‘If someone is in front of you and you don’t vaccinate, you miss an opportunity.’” No matter how well-intentioned the patient is, they may not return to the pharmacy as planned. “The CDC is very clear that coadministration is safe, and we ought to encourage it,” Sylvester said.

“Remind patients that mild reactions, like a sore arm or a low-grade fever, mean that their immune system is doing what it’s supposed to do.” Whether providing a flu vaccine alone or in conjunction with a COVID-19 vaccine, Sylvester reminded pharmacists to ask patients to remain in the building for 15 minutes in case of a severe reaction.

And what about those patients who are reluctant to receive a flu vaccine—or coadministered flu and COVID-19 vaccines? Health care professionals are guided by science and data, Sylvester said, and although they like to reference facts when talking to patients, it may be better to engage in an emotional, personal conversation.

“If the patient is a grandparent, the pharmacist may say, ‘Fifteen out of every 100,000 people die of the flu—I don’t want the next one to be you. You don’t want your grandkids not to have a grandparent,’” Sylvester said. “We know that strong recommendations from a trusted healthcare professional, like a pharmacist or nurse, increase vaccination rates,”Gregg added.

Sylvester added that he would like pharmacists to remember the following takeaways:

  • Everyone 6 months and older should get a flu vaccine, unless there is a contraindication.
  • Data support the coadministration of the flu vaccine and the COVID-19 vaccine, so pharmacists can feel comfortable administering them at the same time.
  • Because the flu is going to return—and we don’t know how severe it will be, especially with COVID-19—pharmacists should encourage everyone to receive the flu vaccine


  1. Frequently asked influenza (flu) questions: 2021-2022 season. CDC. Updated November 3, 2021. Accessed November 3, 2021. https://www.cdc.gov/flu/season/faq-flu-season-2021-2022.htm#what-virus 
  2. Influenza vaccine for the 2021-2022 season. FDA. Updated October 28, 2021. Accessed November 3, 2021. https://www.fda.gov/vaccines-blood-biologics/lot-release/influenza-vaccine-2021-2022-season 
  3. Quadrivalent influenza vaccine. CDC. Updated August 27, 2021. Accessed November 3, 2021. https://www.cdc.gov/flu/prevent/quadrivalent.htm 
  4. Flucelvax Quadrivalent. Prescribing information. Seqirus; 2021. Accessed November 3, 2021. https://flu.seqirus.com/FlucelvaxCategory/Flucelvax/p/FlucelvaxPre
  5. Timing and spacing of immunobiologics. CDC. Updated August 5, 2021. Accessed November 3, 2021. https://www.cdc.gov/vaccines/hcp/acip-recs/general-recs/timing.html#simultaneous 
  6. Berg S. What to know about coadministration of flu and COVID-19 vaccines. American Medical Association. September 21, 2021. Accessed November 3, 2021. https://www.ama-assn.org/delivering-care/public-health/what-know-about-coadministration-flu-and-covid-19-vaccines 
  7. New influenza vaccine recommendations for 2021-2022 season. American Academy of Family Physicians. September 16, 2021. Accessed November 3, 2021. https://www.aafp.org/news/health-of-the-public/20210916acipflu.html
  8. Mix-ups between the influenza (flu) vaccine and COVID-19 vaccines. Institute for Safe Medication Practices. October 7, 2021. Accessed November 3, 2021. https://www.ismp.org/resources/mix-ups-between-influenza-flu-vaccine-and-covid-19-vaccines 
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