- The flu shot can protect you against the flu, but it's not 100% protective.
- A doctor told INSIDER it's because the vaccine may not match up with the flu viruses actually circulating where you live.
- You should always wash your hands to further reduce your risk of catching the flu.
Experts agree that, unless you have certain allergies, you should get a flu shot every single year. For some people, the flu can lead to serious — even deadly — complications. If you're young and healthy, getting the shot protects the more vulnerable people around you.
But you can still get the flu even if you're vigilant about getting the vaccine. INSIDER spoke with Dr. Malcolm Thaler of New York City's One Medical to find out why.
The flu vaccine isn't perfect.
The flu shot doesn't contain the live flu viruses. It contains either inactivated viruses or particles that looks a lot like the flu to your immune system, according to the Centers for Disease Control and Prevention (CDC). These ingredients prompt your body to develop new antibodies that will protect you if you do come in contact with a real, active flu virus.
Here's the catch: The viruses that cause the flu are always changing. Every year, scientists try to design the flu vaccine so that it matches the actual flu viruses that are circulating in communities, the CDC reports. But since the viruses are a moving target, the vaccine isn't perfect.
"It's not 100% protective," Thaler told INSIDER. "In a year when there’s a good match between the vaccine and the circulating viruses, it reduces your risk of getting the flu somewhere between 40 and 60%. So you still can get the flu."
You can actually see the effectiveness of past vaccines if you visit the CDC's website. During the 2014 to 2015 flu seasons, for example, the vaccine's effectiveness was just 19%. But during the 2010 to 2011 flu season, it was 60% effective. (We won't know how effective this year's vaccine is until later.)
The age and health of the person getting vaccinated can also make a difference in how well the vaccine works, the CDC notes.
But there's some good news: Thaler said that, even if you get the shot and then get the flu, the vaccine still lowers the possibility of serious complications like pneumonia and landing in the hospital.
The vaccine isn't the only way to protect yourself.
Want to further lower your odds of getting the flu? Wash your hands.
"The disease is usually transmitted by sneezing or coughing, but it can also be transmitted by contact," Thaler said. "So if someone sneezes on the bar you're holding on the subway and you grab a hold of that bar and then accidentally touch your face, you can transmit the flu virus. But if you keep washing your hands you can definitely lower the risk of that kind of transmission." (By the way, there's a right way to wash your hands: take notes.)
Thaler also said it's wise to take care of yourself during flu season.
"Anything that boosts the health of your immune system, like reducing stress, exercising regularly, eating real foods, getting enough sleep — all that's going to be helpful," he said.
Got more questions about the flu shot? Read more at the CDC website.
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