graphic illustration of a day calendar with the words "Today" printed across the top & the words "Get Flu Vaccine" hand written & circled


While the United States remains focused on the COVID-19 pandemic, we need to also be aware of flu season as we approach winter. Influenza (flu) viruses typically spread in fall & winter, with activity peaking between December & February. Getting vaccinated now can lower your chances of getting the flu.

Flu is a serious disease, caused by influenza viruses, that can lead to hospitalization & even death. Every flu season is different, & the substantial health impacts can vary widely from season to season, with some flu seasons being worse than others. Your best defense is vaccination, which provides important protection from flu & its potential complications.

The flu vaccines approved by the U.S. Food & Drug Administration (FDA) provide important benefits. The Centers for Disease Control & Prevention (CDC) estimate that during the 2018-19 flu season, vaccination prevented 4.4 million flu illnesses, 58,000 hospitalizations, & 3,500 flu-related deaths.

COVID-19 & Flu

It’s likely that flu viruses & the virus that causes COVID-19 will circulate together this fall & winter. The flu vaccine will not prevent COVID-19. The flu vaccines are approved by the FDA for the prevention of influenza disease, so getting vaccinated can help keep you out of the doctor’s office & preserve health care resources for patients with other diseases & medical conditions, including COVID-19.

The FDA plays a key role in ensuring that safe & effective flu vaccines are available every flu season. Flu viruses are spread by droplets when people infected with the flu cough, sneeze, or talk. Flu may also be spread when a person touches a surface or object that has flu viruses on it & then touches their own mouth, nose, or eyes.
It’s best to get immunized early in the flu season.

The CDC recommends that adults & children older than 6 months should get a flu vaccine by the end of October. Even if you wait until after October, go get your flu vaccine. It’s still beneficial because it can protect you for the remainder of the flu season. For more information on vaccines, immunization & where to get vaccinated, visit

If you have already been sick with the flu this season without getting vaccinated, a flu vaccine is still recommended, because the flu vaccine prevents three or four different flu virus strains, depending on which vaccine you receive. Presumably, you were infected with one type of flu virus strain, so the flu vaccine would still offer protection against the flu virus strains that you haven’t already had.

A Flu Vaccine Is the Best Prevention

Flu seasons & their severity are unpredictable. Annual vaccination is the best way to prevent influenza in people ages 6 months & older.

An annual vaccination to prevent flu is the best way to reduce the risk of getting the flu & spreading it to others. When more people get vaccinated, it is less likely that the flu viruses will spread through a community.

The vaccine typically changes each year & contains flu virus strains that are expected to be prevalent during the upcoming flu season. The effectiveness of influenza vaccines varies depending on several factors, such as the age & health of the recipient, the types of circulating influenza viruses, & the degree of similarity between circulating viruses & those included in the vaccine.

The task of producing a new vaccine for the next flu season starts well before the current season ends. For the FDA, it’s a year-round initiative.

The flu vaccine will trigger your immune system to produce antibodies that can protect against influenza disease — it will not make you sick with the flu. It can take about two weeks after vaccination for antibodies to develop in the body, which is an important reason to get your flu vaccine before flu activity starts.

Why We Need New Flu Vaccines Every Year

According to the FDA’s Office of Vaccines Research & Review, there are several reasons a new flu vaccine must be made each year.

Flu viruses can change from year to year, so the vaccine is updated to protect against new virus strains that are expected to circulate in the United States. The vaccine needs to include influenza virus strains that most closely match those in circulation for the influenza season. In addition, the protection provided by the flu vaccine a person received in the previous year will diminish over time & may be too low to prevent influenza disease into next year’s flu season.

Who’s Most at Risk of Getting the Flu

Typically, children & older people are most at risk of getting sick with influenza. The best way to protect babies who are too young to be vaccinated is to make sure people around them are vaccinated.

Occasionally, a flu virus will circulate that disproportionately affects young & middle-age adults.

You also can reduce the spread of the flu & its effects by taking such practical measures as washing your hands, covering coughs & sneezes, & staying home when you’re sick.

The FDA has approved numerous vaccines for the prevention of influenza. But if you do get the flu, there are FDA-approved antiviral drugs, available by prescription, to treat your illness. There are several FDA-approved antiviral drugs recommended by the CDC for use against circulating influenza viruses. These drugs work best if started soon after the onset of symptoms (within 48 hours).

How Flu Vaccine Virus Strains Are Selected

Each February, before that year’s flu season ends, the FDA, the World Health Organization (WHO), the CDC, & other public health experts collaborate on collecting & reviewing data from around the world to identify the flu viruses likely to cause the most illnesses during the next flu season.

Following that process, the FDA convenes its vaccines advisory committee, consisting of outside experts, to provide advice to the FDA on the upcoming U.S influenza season. Committee members discuss the WHO recommendations & consider which flu viruses are expected to circulate in the United States. They also review data about which flu viruses have caused illnesses in the past year, how the viruses are changing, & disease trends for the United States. The FDA takes that information into account before it selects the virus strains for FDA-licensed manufacturers to include in their vaccines for use in the United States.

The closer the match between the virus strains chosen for the vaccine & the circulating strains causing disease during flu season, the better the protection that the flu vaccine provides. Although the vaccine & viruses may not be an exact match in some years, that does not mean the vaccine is not benefiting people. We know from past studies that the vaccine can still provide enough protection in people who received it to help make their illness milder or prevent flu-related complications.

The Flu Vaccine Is Safe

To ensure that the flu vaccine is safe, effective, & of high quality, the FDA prepares & provides reagents (materials to standardize vaccines) to manufacturers that they need to make their vaccine & to verify its identity & potency. The FDA also inspects manufacturing facilities regularly & evaluates each manufacturer’s vaccine annually before it can be approved.

The FDA’s oversight doesn’t end there. After manufacturers have distributed their vaccines for use by the public, the FDA & CDC scientists work together to routinely evaluate reports submitted by companies, health care providers, parents, & patients to the Vaccine Adverse Event Reporting System (VAERS) of health problems that may be associated with a vaccine.

Additional methods are in place to monitor vaccine safety. The FDA monitors the safety of influenza & other vaccines utilizing the Sentinel Post Licensure Rapid Immunization Safety Monitoring (PRISM) system, which enables the FDA to proactively assess vaccine safety, under real-world conditions, reflecting patient care in the U.S.
& the CDC maintains the Vaccine Safety Datalink (VSD), which provides nearly real-time monitoring of people who are vaccinated, in collaboration with nine integrated health care organizations.

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