December 8, 2019 - Haven’t had your flu vaccine 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 the substantial health impacts can vary widely from season to season. Your best defense is vaccination, which provides important protection from influenza illness and its potential complications.
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.
The Centers for Disease Control and Prevention (CDC) estimates that during the severe 2017-18 influenza season, vaccination prevented 7.1 million illnesses, 3.7 million medical visits, 109,000 hospitalizations, and 8,000 deaths associated with flu. That flu season was notable for an unusually long period of widespread and high influenza activity throughout the United States and higher rates of outpatient visits and hospitalizations compared with recent seasons.
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 and then touches their own mouth, nose, or eyes. Although influenza viruses circulate year-round, flu activity peaks between December and February most years. The season can last as late as May in the United States.
It’s best to get immunized early in the flu season. The CDC recommends that adults and children older than 6 months should get a flu vaccine by the end of October. Even if you have waited until after October, go get your vaccine. It’s still beneficial because it can protect you for the remainder of the flu season.
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 to four different flu virus strains. 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 had.
Even if you still get the flu after vaccination, the vaccine can help because it can reduce the severity of illness in people who get vaccinated but still get sick.
A Flu Vaccine Is the Best Prevention Method
Flu 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 to reduce the 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 effectiveness of influenza vaccines varies depending on several factors, such as the age and health of the recipient, the types of circulating influenza viruses, and the degree of similarity between circulating viruses and those included in the vaccine.
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 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 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. 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 previous year’s vaccine will diminish over time and may be too low to prevent influenza disease into the next year.
Who’s Most at Risk of Getting the Flu?
Typically, children and 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 and middle-age adults.
The FDA 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 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.
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, 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 process, 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 inclusion in the vaccine and the circulating strains causing disease during flu season, the better the protection that the flu vaccine provides. Although the vaccine and viruses may not be an exact match in some years, that does not mean the vaccine is not benefiting people. We know from past influenza season studies that the vaccine can still provide enough protection in people who received the vaccine that season 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, and of high quality, the FDA prepares and provides reagents (materials to standardize vaccines) to manufacturers that they need to make their vaccine and to verify its identity and potency. The FDA also inspects manufacturing facilities regularly and 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 and CDC scientists work together 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 utilizing the Sentinel Post Licensure Rapid Immunization Safety Monitoring (PRISM) External Link Disclaimersystem, which enables FDA to proactively assess vaccine safety, under real-world conditions, reflecting patient care in the U.S.
And the CDC maintains the Vaccine Safety Datalink (VSD), which provides nearly real-time monitoring of people who are vaccinated, in collaboration with eight integrated health care organizations.