Every year, health officials warn people to get their flu shots. Every year, people ignore those calls.
Just 37 percent of U.S. adults were estimated to have been vaccinated last flu season, down 6 percentage points from the year before, according to the Centers for Disease Control and Prevention. Meanwhile, the CDC estimates the flu killed more than 80,000 people and caused more than 900,000 hospitalizations last year.
"Getting the flu vaccine is better than getting the flu," said Dr. Deborah Lehman, a professor of pediatrics at the David Geffen School of Medicine at the University of California, Los Angeles. "As someone who has watched children die from the flu and heard of adults dying from the flu, it's hard for me to reconcile."
Here are some common misconceptions people have about the flu vaccine and the truth behind them.
Over the past decade, the flu shot has been 44 percent effective, on average, according to a review of CDC data.
Health officials meet every February to choose which strains to include the year's flu shot. Even if they pick a good match, the virus often mutates, so much so that the vaccine elicits immune responses that do not recognize the illness and therefore struggle to fight it.
So yes, you still can get the flu if you get a shot. But the vaccine is still currently the best way to protect yourself. And even when people who got the shot end up getting sick, their illnesses tend to be less severe.
"It's not perfectly successful, but it does reduce your odds of getting it and lessens your chance of being in the hospital or the morgue," said Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia and a vaccinology professor at the Perelman School of Medicine at the University of Pennsylvania.
Yes, the shot is made from the flu virus — but it's inactivated, making it impossible for the vaccine to give you the flu.
When developing the vaccine, scientists include two surface proteins from the virus, said Offit. That way, when a person gets the shot, his or her immune system's antibodies can learn how to fight the flu without ever being exposed to it, he said.
The vaccine is essentially a practice round for your immune system. Some people experience a sore arm or low-grade fever after the shot because their bodies are learning to fight.
"It's much better to get a little bit of a sore arm than spending three or four days stuck in bed not wanting to eat and drink because you have the actual flu," said Dr. Aaron Milstone, an associate hospital epidemiologist at The Johns Hopkins Hospital .
It's true that the very young and very old are most susceptible to dying from the flu. However, that doesn't make everyone in between invincible.
Influenza can wreck havoc on the body. The upper respiratory illness can cause people to experience a fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, fatigue and sometimes diarrhea and vomiting, according to the CDC.
It can lead to complications like pneumonia, which can be serious. The combination of influenza and pneumonia was the eighth leading cause of death in 2016, killing 51,537 people that year, according to the CDC.
Health researchers also have seen evidence that there is an increased risk of heart attack and stroke as people recover from the illness.
Also, even if you're young and healthy, you can spread the flu to someone who's not. Seemingly healthy adults might be able to infect other people one day before their symptoms develop and up to five to seven days after becoming sick, according to the CDC.
"Often one of the most convincing arguments is you're healthy, but what about grandma or a little baby?" said Dr. Richard Webby, a member of the infectious diseases department at St. Jude Children's Research Hospital and the World Health Organization's Vaccine Composition Team. "There's a chance you'll transmit the virus to others that are high risk. By vaccinating yourself, you may actually protect others, as well."
Flu activity tends to increase in October and November and can last as late as May, according to the CDC. The agency recommends getting vaccinated by the end of October because it takes two weeks for antibodies that fight the flu to develop in your body. So at this point, you may be a little late, but the CDC says it's still beneficial to get the shot later than not at all.