The CDC recommends that flu “vaccine should continue to be offered to unvaccinated people throughout the flu season as long as vaccine is still available.” They also state that “as long as flu viruses are spreading, it’s not too late to get a vaccine to protect yourself and your loved ones.”

So it is really never too late to get a flu vaccine.

Haven’t had your flu shot yet? It’s not too late. And there are still good reasons to get one.

Flu — more formally known as influenza — is a serious viral disease that can lead to hospitalization and even death. Every flu season is different, and last year’s broke records. The Centers for Disease Control and Prevention (CDC) estimates that more than 900,000 people were hospitalized, and that more than 80,000 people died from flu during the 2017-18 season.

Flu viruses are spread by droplets when people infected with the flu cough, sneeze or talk. Flu also is spread by touching a surface or object that has flu viruses on it. Although influenza viruses circulate year-round, flu activity peaks between December and February most years, but can last as late as May in the United States.

It’s best to get immunized early in the flu season. The CDC says all adults and children older than 6 months should get a flu vaccine by the end of October. Even if you waited until after October, go get your vaccine. It’s still beneficial.

A Flu Vaccine Is the Best Prevention Method

Influenza seasons and severity are unpredictable. Annual vaccination is the best way to prevent influenza for people ages 6 months and older.

An annual immunization with flu vaccine is the most effective and safest way for most of us to reduce our risk of getting the flu and 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 and contains flu virus strains that are expected to be prevalent during the upcoming flu season. The 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.

The U.S. Food and Drug Administration (FDA) plays a key role in ensuring that safe and effective flu vaccines are available every flu season. In fact, 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.

Why We Need a New Flu Vaccine Every Year

According to the FDA’s Office of Vaccines Research and 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 may need to be updated to protect against new virus strains. Experts meet each year to recommend strains for the next year’s vaccine. Their goal is to choose influenza virus strains that will most closely match those that are anticipated to be in circulation during the next flu season. In addition, the protection provided by the previous year’s vaccine will diminish over time and may be too low to provide protection into the next year.

Who’s Most at Risk of Getting the Flu

Typically, children and older people are most at risk for 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 and middle-age adults.

The FDA also urges health care organizations to ensure that influenza vaccination programs are available for health care professionals to help decrease the likelihood of contracting influenza and inadvertently infecting others.

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

Although vaccines can help prevent the flu, antiviral drugs are an important tool that can help to treat it. There are several FDA-approved antiviral drug products 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).

Identifying Flu Virus Strains

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

Following that, the FDA convenes its advisory committee to discuss the WHO recommendations. The committee also reviews data about which flu viruses have caused illnesses in the past year, how the viruses are changing, and disease trends for the United States. Based on that information, the agency 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 influenza virus strains chosen for the vaccine and the circulating strains causing disease during flu season, the better the protection that the flu vaccine provides. In some years, the vaccine and viruses may not be an exact match. Still, it does not mean the vaccine is not benefiting people. We know from past influenza studies that the vaccine can still provide enough protection to make symptoms milder or prevent flu-related complications.

The Flu Vaccine Is Safe

To ensure the flu vaccine is safe, effective, and of high quality, the FDA provides manufacturers with the seed viruses used to make and test the vaccine, ensuring it meets standards of identity and potency. The FDA also inspects manufacturing facilities regularly and evaluates each manufacturer’s vaccine annually for approval purposes.

The FDA’s oversight doesn’t end there. After manufacturers have distributed their vaccines for use by the public, the FDA works with CDC scientists to routinely evaluate reports 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 conducts influenza and other vaccine surveillance within the Sentinel Post Licensure Rapid Immunization Safety Monitoring (PRISM)system.

And 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.