Every year, millions of people in the United States contract the flu. Many people recover from the illness, but some require hospitalizations. And, unfortunately, every year some people die of flu-related complications.

Dr. Tina Ardon, a Mayo Clinic family medicine specialist, said that the flu vaccine is the best defense against seasonal flu and that everyone who is able to get one should do so.

Seasonal flu is a virus that attacks your respiratory system. Most people get better on their own, but the flu can be serious for some.

“Our younger children and our older adults definitely can get more sick from the flu,” Ardon said. “Patients who are already sick with other chronic conditions, or are undergoing chemotherapy, are more likely to have complications.”

Those complications include bronchitis, pneumonia and heart problems.

“The vaccine for influenza is one of the best defenses we have,” Ardon said.

She said some people don’t get the flu vaccine because they think it could cause the flu. But “the flu vaccine is what we call a dead vaccine.”

That means that you can’t get the flu from a flu shot. FluMist, while safe for most people, contains a weakened form of the virus, so people with certain conditions should get a shot instead.

It takes two weeks for the vaccine to work, so get your flu shot now.