Frequently Asked Influenza (Flu) Questions: 2021-2022 Season

What’s New for 2021-2022

A few things are different for the 2021-2022 influenza (flu) season, including:

  • The composition of flu vaccines has been updated.
  • All flu vaccines will be quadrivalent (four component), meaning designed to protect against four different flu viruses. For more information: Quadrivalent Influenza Vaccine | CDC.
  • Licensure on one flu vaccine has changed. Flucelvax Quadrivalent is now approved for people 2 years and older.
  • Flu vaccines and COVID-19 vaccines can be given at the same time.
  • More detailed guidance about the recommended timing of flu vaccination for some groups of people is available.
  • Guidance concerning contraindications and precautions for the use of two flu vaccines – Flucevax Quadrivalent and Flublok Quadrivalent – were updated.

Flu Vaccine

Annual flu vaccination is recommended for everyone 6 months and older, with few exceptions.

There are many different flu viruses, and they are constantly changing. The composition of US flu vaccines is reviewed annually and updated as needed to match circulating flu viruses. This season, all flu vaccines will be designed to protect against the four viruses that research indicates will be most common. Each year, the Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) makes the recommendation for the flu vaccine composition for US flu vaccines.

For 2021-2022, recommendations were made for egg-based, cell-based, and recombinant flu vaccines as listed below:

Egg-based vaccine composition recommendations:

  • an A/Victoria/2570/2019 (H1N1) pdm09-like virus;
  • an A/Cambodia/e0826360/2020 (H3N2)-like virus;
  • a B/Washington/02/2019- like virus (B/Victoria lineage);
  • a B/Phuket/3073/2013-like virus (B/Yamagata lineage)

Cell- or recombinant-based vaccine composition recommendations:

  • an A/Wisconsin/588/2019 (H1N1) pdm09-like virus;
  • an A/Cambodia/e0826360/2020 (H3N2)-like virus;
  • a B/Washington/02/2019- like virus (B/Victoria lineage);
  • a B/Phuket/3073/2013-like virus (B/Yamagata lineage).

These recommendations include two updates compared with 2020-2021 US flu vaccines. Both the influenza A(H1N1) and the influenza A(H3N2) vaccine virus components were updated. Compared with the Southern Hemisphere flu vaccine recommendation, this recommendation represents one update and that is to the influenza A(H3N2) component.

For more information, visit Influenza Vaccine for the 2021-2022 Season | FDAexternal icon

All available flu vaccines in the United States this flu season are quadrivalent (four-component) flu vaccines that are designed to protect against the four flu viruses that research indicates are most likely to spread and cause illness among people during the upcoming flu season. In its role as a World Health Organization (WHO) Collaborating Center, CDC conducts year-round surveillance of circulating flu viruses and uses this and other data to assess population risk and to recommend the vaccine viruses to include in vaccine production for both the Southern and Northern Hemispheres. Flu viruses constantly change and, based on the available data on how flu viruses are currently changing, CDC flu experts anticipate that the flu viruses that circulate this season may have small changes in comparison to each of the four major virus components used in the vaccine. Despite these changes, the flu vaccine is still expected to provide good protection for the majority of flu viruses that are likely to circulate in the United States during the upcoming flu season. Since flu viruses change rapidly, some changes can result in decreased similarity between circulating viruses and one of the vaccine’s four components. The similarity of the vaccine’s four components to the flu viruses that circulated during previous seasons is just one of several types of data used to inform the recommendations for the composition of flu vaccines. Other data include the extent and location of flu virus circulation and the level of immunity in the population provided by the prior season’s vaccine against recent circulating flu viruses. CDC constantly reviews the composition of flu vaccines and suggests updates when needed to keep up with the latest flu viruses. Sometimes, updates to the composition of the flu vaccine represent minor, incremental improvements. Other times, the updates to the vaccine can represent more significant changes intended to provide optimal protection against flu viruses that have evolved to evade people’s existing immunity.

In general, updates to the composition of Southern Hemisphere flu vaccines should not be interpreted to mean that the composition of Northern Hemisphere flu vaccines is mismatched to circulating flu viruses. The flu season occurs at different times in each hemisphere. Typically flu season lasts from October to May in the Northern Hemisphere and from April to September in the Southern Hemisphere. Decisions on the composition of flu vaccines must be made months prior to the flu season in each hemisphere so that flu vaccines can be produced and made available in time for the season. Since flu viruses are always changing, different flu viruses can circulate in different geographic areas of the world at different times of the year. As a result, separate recommendations are made for the flu vaccines produced in the Northern and Southern Hemispheres based on the data available at the time vaccine composition recommendations are made. The flu vaccines for each hemisphere are optimized to protect against the flu viruses that research indicates will circulate during the upcoming flu season in each hemisphere.

Several flu vaccine formulations are approved for use in people 65 and older, including two “enhanced” flu vaccines: the high-dose flu vaccine and the adjuvanted flu vaccine, both of which are designed to create a stronger immune response in people 65 years and older. Also, a recent studyexternal icon showed that recombinant flu vaccine can produce a stronger immune response in people 65 years and older. Additionally, there are standard dose flu vaccines that can be used in people 65 and older. It’s important to note that CDC does not have a preferential recommendation for any flu vaccine over another, and vaccination should not be delayed for a specific vaccine product when another vaccine licensed for use in people 56 and older is available.

CDC recommends use of any licensed, age-appropriate flu vaccine during the 2021-2022 flu season, including inactivated flu vaccinehigh-dose flu vaccineadjuvanted flu vaccine, recombinant flu vaccine, and nasal spray flu vaccine. Vaccination should not be delayed for a specific vaccine product when another age-appropriate vaccine is available.

CDC has annual educational campaigns to increase awareness about the importance of seasonal flu vaccination. For the 2021-2022 season, CDC will continue to emphasize the importance of flu vaccination beginning in September and for the entire flu season. The agency will conduct targeted communication outreach to specific groups of people who are at higher risk for developing serious complications from flu. Communication strategies for providers and the public will include:

  • Educational outreach activities by CDC, including social media, press conferences, web page spotlights, radio media tours, op-eds, and other publications,
  • Special educational efforts and a digital campaign to inform the general population, people with underlying health conditions, and African American and Hispanic audiences about the importance of flu vaccination, and
  • Updated vaccination websites for the public and providers that highlight the safety precautions being implemented in health care facilities during the COVID-19 pandemic.

In addition, as part of its new Partnering for Vaccine Equity program, CDC is providing more than $150 million in funding to support national, state, local, and community-level partners working to increase confidence in COVID-19 and flu vaccines among adults in racial and ethnic minority groups.

If you don’t have a health care professional you regularly see, you can find flu vaccines at many places, including health departments and pharmacies.

September and October are generally good times to be vaccinated. Ideally, everyone should be vaccinated by the end of October. Adults, especially those older than 65, should not get vaccinated early (in July or August) because protection in this group may decrease over time. Children can get vaccinated as soon as vaccine becomes available—even if this is in July or August.  Some children need two doses.  For those children it is recommended to get the first dose as soon as vaccine is available, because the second needs to be given at least 4 weeks after the first.  Early vaccination can also be considered for people who are in the third trimester of pregnancy, because this can help protect their infants during the first months of life (when they are too young to be vaccinated).

Flu Activity

Flu viruses are constantly changing so it’s not unusual for new flu viruses to appear each year. More information about how flu viruses change is available.

The timing of flu is difficult to predict and can vary in different parts of the country and from season to season. Reduced population immunity due to lack of flu virus activity since March 2020 could result in an early and possibly severe flu season. 

No. You should not wait for flu activity to be rising or high in your community to get a flu vaccine. September and October are generally good times to be vaccinated and ideally, everyone should be vaccinated before the end of October. While flu activity may be low in your community now, it could begin increasing at any time. Remember, after you are vaccinated, your body takes about two weeks to develop antibodies that protect against flu. Ideally, you should get vaccinated against flu by the end of October.

Flu Vaccine Coverage

CDC has developed a Weekly National Flu Vaccination Dashboard designed to share preliminary, in-season, weekly flu vaccination coverage estimates and related data.

The dashboard will include information on the number of flu vaccine doses distributed in the United States, weekly flu vaccination coverage rates for children 6 months – 17 years old, monthly flu vaccination coverage rates among pregnant persons, and information on how many flu vaccines have been administered in pharmacies and doctor’s offices.

The data will be updated weekly or monthly, depending on the data source, throughout the 2021-2022 flu season; other data sources will be added as they become available. Visit the National Flu Vaccination Dashboard for more information.

CDC also provides seasonal flu vaccination coverage estimates at the end of a flu season. However, those estimates are not usually available until several months after the flu season ends.

Flu vaccination coverage among children is assessed through the National Immunization Survey-Flu (NIS-Flu), which provides weekly flu vaccination coverage estimates for children 6 months–17 years old. NIS-Flu is a national random-digit-dialed cellular telephone survey of households conducted during the flu season (October-June). Additional information about NIS-Flu methods and estimates from 2019-2020 season are available at FluVaxView.

Monthly flu vaccination coverage estimates among pregnant people are based on electronic health record (EHR) data from the Vaccine Safety Datalink (VSD), a collaboration between CDC’s Immunization Safety Office and nine integrated health care organizations. Of note, because these estimates are based on data from nine integrated health care systems, they may not be representative of all pregnant persons in the U.S.

CDC is tracking the number of flu vaccines administered at pharmacies and doctor’s offices by utilizing new sources of vaccination data, including IQVIAnexternal icon data for vaccinations administered in retail pharmacies (e.g., chain, mass merchandise, food stores, and independent pharmacies) and doctors’ offices.

CDC will launch the first weekly FluVaxView dashboard in December. The number of flu vaccine doses distributed, vaccination coverage estimates for children, and vaccinations administered in retail pharmacies and doctors’ offices will be updated weekly. Coverage estimates for pregnant persons will be updated monthly. Visit the National Flu Vaccination Dashboard for more information.

Each flu season since 2009-2010, CDC has estimated annual flu vaccination coverage for the United States by utilizing data from several nationally representative surveys: the Behavioral Risk Factor Surveillance System (BRFSS), the National Health Interview Survey (NHIS), and the National Immunization Survey-Flu (NIS-Flu). Internet panel surveys of adultshealth care personnel, and pregnant persons are also used.

Click here for vaccination coverage estimates from past flu season. CDC will continue to provide end-of-season estimates of flu vaccination coverage from these data sources.

For the 2021-22 flu season, CDC will provide weekly updates on the number of flu vaccine doses distributed, vaccination coverage estimates for children, and the number of doses administered in pharmacies and doctors’ offices. Coverage estimates for pregnant persons will be updated monthly.

 CDC is exploring non-survey data sources, such as claims and other administrative data, to track flu vaccination coverage.  For example, CDC is exploring ways to estimate within-season flu vaccination coverage among adults using data on the number of doses administered in pharmacies and doctor’s offices and estimates of the proportion of all flu vaccinations that are received in these settings.  CDC supports state and local jurisdictions in use of their immunization information systems to assess flu vaccination coverage at the jurisdictional level.

Seasonal Flu and COVID-19

Flu and COVID-19 are both contagious respiratory illnesses, but they are caused by different viruses. COVID-19 is caused by infection with a coronavirus (called SARS-CoV-2) and seasonal flu (most often just called “flu”) is caused by infection with one of many influenza viruses that spread annually among people.

Because some symptoms of flu and COVID-19 are similar, people may need to be tested to tell what virus is causing their illness. People can be infected with both a flu virus and the virus that causes COVID-19 at the same time. In general, COVID-19 seems to spread more easily than flu and causes more serious illnesses in some people. Compared with people who have flu infections, people who have COVID-19 can take longer to show symptoms and be contagious for longer. This FAQ page compares COVID-19 and flu, given the best available information to date.

While it’s not possible to say with certainty what will happen in the fall and winter, CDC believes it’s likely that flu viruses and the virus that causes COVID-19 will both be spreading at that time. Relaxed COVID-19 mitigation measures (such as stay-at-home orders, or mask mandates) may result in an increase in flu activity during the upcoming 2021–2022 flu season. Common respiratory viruses such as respiratory syncytial virus (RSV) and human coronaviruses (not SARS-CoV-2) did not spread as much as usual during the 2020-2021 flu season as in past seasons. However, data from the National Respiratory and Enteric Surveillance System (NREVSS) showed an increase in these viruses’ activity during the summer, outside of their usual seasonal increases. This information is summarized in a Morbidity and Mortality Weekly Report, Changes in Influenza and Other Respiratory Virus Activity During the Pandemic.

Yes. It is possible to have flu and other respiratory illnesses like COVID-19 at the same time. Health experts are still studying how common this is. Some of the symptoms of flu and COVID-19 are similar, making it hard to tell the difference between them based on symptoms alone. Diagnostic testing can help determine if you are sick with flu or COVID-19.

Because COVID-19 is still a relatively new illness, we have little information about how flu illness might affect a person’s risk of getting COVID-19. We do know that people can be infected with flu viruses and the virus that causes COVID-19 at the same time. Getting a flu vaccine is the best protection against flu and its potentially serious complications, and getting a COVID-19 vaccine is the best protection against COVID-19.

Your health care professional may order a test to help confirm whether you have flu or COVID-19 or some other illness. Get more information on COVID-19 and flu testing and symptoms of COVID-19 and flu.

Yes. There are tests that will check for seasonal influenza A and B viruses and SARS-CoV-2, the virus that causes COVID-19. Testing for these viruses at the same time gives public health officials important information about how flu and COVID-19 are spreading and what prevention steps people should take. These tests also help public health laboratories save time and testing materials, and possibly return test results faster. More information for laboratories is available.

Flu vaccines are not designed to protect against COVID-19. Flu vaccination reduces the risk of flu illness, hospitalization and death in addition to  other important benefits.

Likewise, getting a COVID-19 vaccine is the best protection against COVID-19, but those vaccines are not designed to protect against flu. Visit the CDC’s Frequently Asked Questions page for information about COVID-19 vaccinations.

No. There is no evidence that getting a flu vaccination raises your risk of getting sick from COVID-19 or any other coronavirus. (Common human coronaviruses usually cause mild to moderate upper-respiratory tract illnesses, like the common cold.)

Health care professionals may have different practices for diagnosing and treating flu during the COVID-19 pandemic, such as wearing masks in a health care setting or offering telemedicine. If you have flu symptoms and are at higher risk of serious flu complications, you should call your health care professional as soon as possible to tell them about your symptoms. They may decide to treat you with flu antiviral medications. Follow your health care professional’s and CDC’s recommendations for doctor visits.

Getting a Flu Vaccine During the COVID-19 Pandemic

Yes. Getting a flu vaccine is an essential part of protecting your health and your family’s health every year. Take recommended precautions to protect yourself from COVID-19 while getting your flu vaccine.

Yes. Wearing a mask and physical distancing can help protect you and others from respiratory viruses, like flu and the virus that causes COVID-19. However, the best way to reduce your risk of flu illness and its potentially serious complications is for everyone 6 months and older to get a flu vaccine each year. By getting a flu vaccine, you may also be protecting people around you who are more vulnerable to serious flu complications.

Yes, you can get a COVID-19 vaccine and a flu vaccine at the same time.

Even though both vaccines can be given at the same visit, people should follow the recommended schedule for either vaccine: If you haven’t gotten your currently recommended doses of COVID-19 vaccine, get a COVID-19 vaccine as soon as you can, and ideally get a flu vaccine by the end of October.

While limited data exist on giving COVID-19 vaccines with other vaccines, including flu vaccines, experience with giving other vaccines together has shown the way our bodies develop protection and possible side effects are generally similar whether vaccines are given alone or with other vaccines.

If you have concerns about getting both vaccines at the same time, you should speak with a health care provider.

Information for Healthcare Professionals

Administering Flu Vaccine during the COVID-19 Pandemic

Curbside and drive-through vaccination clinics may provide the best option for staff and patient safety during the COVID-19 pandemic in communities with high transmission. Read CDC’s guidance on drive-through vaccination clinics.

No. Flu vaccination should be deferred for people with suspected or confirmed COVID-19, whether or not they have symptoms, until they have met the criteria to discontinue their isolation. While mild illness is not a contraindication to flu vaccination, vaccination visits for these people should be postponed to avoid exposing healthcare personnel and other patients to the virus that causes COVID-19. When scheduling or confirming appointments for flu vaccination, patients should be instructed to notify the health care professional’s office or clinic in advance if they currently have or develop any symptoms of COVID-19.

Flu vaccination should be deferred until a patient is no longer acutely ill. This may be different for patients who are already being cared for in a medical setting than it is for patients who are isolating at home. In a medical setting, the timing for vaccination is a matter of clinical discretion. In general, patients who are isolating at home should wait until they meet criteria for leaving isolation (even if they have no symptoms) to come to a vaccination setting in order to avoid spreading COVID-19 to others. CDC has guidance for when people can be around others after having COVID-19.

CDC released Interim Guidance for Immunization Services During the COVID-19 Pandemic. This guidance is intended to help vaccination providers in a variety of clinical and alternative settings with the safe administration of vaccines during the COVID-19 pandemic. This guidance will be continually reassessed and updated based on the evolving epidemiology of COVID-19 in the United States. Healthcare professionals who give vaccines should also consult guidance from state, local, tribal, and territorial health officials.

Clinicians, for more information visit, Seasonal Influenza Vaccine Dosage & Administration | CDC

Yes. If a patient is eligible, both influenza and COVID-19 vaccines can be administered at the same visit, without regard to timing as recommended by CDC and its Advisory Committee on Immunizations Practices (ACIP). If a patient is due for both vaccines, providers are encouraged to offer both vaccines at the same visit. Coadministration of all recommended vaccines is important because it increases the probability that people will be fully vaccinated. It is also an important part of immunization practice if a health care provider is uncertain that a patient will return for additional doses of vaccine.

Best practices for administering more than one vaccine, including COVID-19 vaccines and influenza vaccines, include:

  • When preparing more than one vaccine, label each with the name and dosage (amount) of vaccine, lot number, the initials of the preparer, and the exact beyond-use time, if applicable.
  • Always inject vaccines into different injection sites. Separate injection sites by 1 inch or more, if possible so that any local reactions can be differentiated. Each muscle (deltoid, vastus lateralis) has multiple injection sites.

You can get your flu vaccine as you normally do, whether that’s through your health care provider or your local pharmacist. CDC has been working with health care providers and state and local health departments on how to vaccinate people against flu without increasing their risk of exposure to respiratory viruses, like the virus that causes COVID-19, and has released Interim Guidance for Immunization Services During the COVID-19 Pandemic. More information is available in the ‘Administering Flu Vaccines during the COVID-19 Pandemic’ section below. This guidance is current for this season.

Applying infection prevention practices to all patient encounters is very important, including physical distancing (at least 6 feet) when possible, wearing masks, hand hygiene, surface decontamination, and source control while in a health care facility. The potential for asymptomatic spread of the virus that causes COVID-19 underscores the importance of these practices. Immunization providers should refer to the guidance developed to prevent the spread of COVID-19 in health care settings, including outpatient and ambulatory care settings.

Yes. Guidance has been developed for giving vaccines at pharmacies, temporary, off-site, or satellite clinicspdf iconexternal icon, and large-scale influenza clinics. Other approaches for vaccination during the COVID-19 pandemic may include drive-through immunization services at fixed sites, curbside clinics, mobile outreach units, and home visits.

Curbside and drive-through vaccination clinics may provide the best option for staff and patient safety during the COVID-19 pandemic in communities with high transmission. Read CDC’s guidance on drive-through vaccination clinics.

Testing and Treatment of Respiratory Illness when SARS-CoV-2 and Influenza Viruses are Co-circulating

While waiting on results of testing, non-hospitalized persons with acute respiratory symptoms should self-isolate at home. Even if people test negative for both SARS-CoV-2 and influenza viruses, they should self-isolate because of the potential for false negative testing results – depending upon what kind of test was done (e.g., antigen test, molecular test) and the level of SARS-CoV-2 and influenza virus transmission in the community. Persons not hospitalized with suspected or confirmed influenza who are at increased risk for complications from influenza should receive antiviral treatment for influenza as soon as possible, regardless of illness duration.

For hospitalized patients, empiric oseltamivir treatment should be started as soon as possible for patients with suspected influenza without waiting for influenza testing results. Get more information on testing and treatment when SARS-CoV-2 and flu viruses are co-circulating.

CDC has developed clinical algorithms that can help guide decisions for influenza testing and treatment when SARS-CoV-2 and influenza viruses are co-circulating.

FDA-approved antiviral medications for treatment of influenza have no activity against SARS-CoV-2 viruses, nor do they interact with medications used for treatment of COVID-19 patients. If a patient who is at higher risk for influenza complications is diagnosed with SARS-CoV-2 and influenza virus co-infection, they should receive antiviral treatment for influenza.