Subscribe: FDA Consumer Health Information
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. Although every flu season is different, flu has resulted in anywhere from 9.2 million to 35.6 million illnesses; 140,000 to 710,000 hospitalizations; and 12,000 to 56,000 deaths every year since 2010, according to the Centers for Disease Control and Prevention (CDC).
Flu viruses are spread through tiny droplets by people infected with flu who 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 activity can last as late as May in the U.S.
A Flu Vaccine Can Help
An annual seasonal flu vaccine is the best way to reduce your risk of getting sick and spreading it to others. The vaccine typically is redesigned each year to contain flu virus strains expected to be prevalent during the upcoming flu season. The strains have been inactivated so that they don’t cause you to get sick with flu, but will trigger your immune system to produce antibodies that can protect against influenza disease.
When more people get vaccinated, less flu can spread through a community. It can take about two weeks after vaccination for antibodies to develop in the body.
The U.S. Food and Drug Administration plays a key role in ensuring that safe and effective 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 New Flu Vaccines Every Year
According to the FDA’s Office of Vaccines Research and Review, there are several reasons new flu vaccines must be made each year.
Flu viruses can change from year to year because of different subtypes and strains that circulate each year. A vaccine is needed that includes virus strains that most closely match those in circulation, and the protection provided by the previous year’s vaccine will diminish over time.
Who’s Most at Risk of Getting the Flu
Typically, children and older people are most at risk for influenza, but occasionally a flu virus will circulate that disproportionately affects young and middle-age adults.
Influenza seasons and severity are unpredictable. Annual vaccination is the best way to prevent influenza among people ages 6 months and older. You also can reduce the spread of the flu and reduce its effects by taking such practical measures as washing your hands, covering coughs and sneezes, and staying home when you’re sick.
Although antiviral drugs are not a substitute for vaccines, they can help to treat influenza. There are several FDA-approved antiviral drug products recommended by CDC for use against recently circulating influenza viruses.
Identifying Flu Virus Strains
Each February, before that year’s flu season ends, the FDA, the World Health Organization, 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. Based on that information and the recommendations of an FDA advisory committee, 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 virus strains chosen for the vaccine and what strains are circulating causing disease during the next flu season, the better the protection that the flu vaccines can provide.
To ensure that vaccines are safe, effective, and of high quality, the FDA prepares and provides reagents (materials to standardize vaccines) that vaccine manufacturers need to make their vaccine and to verify its identity and strength. The FDA also inspects the manufacturing facilities regularly and evaluates each manufacturer’s vaccine annually for approval purposes.
Flu Vaccines Are Safe
The FDA’s oversight doesn’t end there. After manufacturers have distributed their vaccines for use by the public, the FDA, working with CDC scientists, routinely evaluates reports to the Vaccine Adverse Event Reporting System (VAERS) of health problems that may be associated with a vaccine. And the FDA and Centers for Medicare and Medicaid Services conduct annual surveillance for Guillain-Barre syndrome, a rare neurological condition associated with the 1976 flu vaccine.
Other avenues exist 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.
Updated: January 10, 2018
back to top