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What's the Flu?

Influenza (say: in-floo-EN-zah) is also called the flu. It's an infection that causes a fever, chills, cough, body aches headaches, and sometimes earaches or sinus problems. It also sometimes cause nausea, vomiting, or diarrhea.

The flu is caused by the influenza virus (say: VY-rus). A virus is a microorganism (say: my-kroh-OR-guh-niz-uhm), which means it's so small that you would need a strong microscope to see it.

What's the Flu Vaccine?

Health experts recommend that all people age 6 months and older get the flu vaccine (say: vak-SEEN) each year. If you're a kid, that means you!

For kids, there are two types of flu vaccines:

  • a flu shot, given with a needle
  • a nasal spray, sprayed into the nose

This flu season (2023–2024) both types seem to work equally well. You should get whatever type of vaccine your doctor suggests. Some kids can't get the spray mist, such as those with weak immune systems or some medical conditions like asthma.

If you get the flu vaccine, it will protect you from getting a bad case of the flu. You either won't get the flu at all, or if you do get it, your symptoms will be mild and you should get better pretty quickly.

Here's what the vaccine means for most kids:

  • Kids older than 9 need only 1 dose.
  • Are you younger than 9?
    • You will need 2 doses if this is your first time getting the vaccine, or if you've only had 1 dose in the past. You'll get the first dose and then come back at least a month later to get the second one.
    • You will need only 1 dose if you've gotten the flu vaccine at least twice in the past. (Your parents and doctor can look this up.)

Some people are at higher risk of problems if they get the flu, including:

  • pregnant women
  • kids younger than age 5
  • people age 65 and older
  • people of any age who have long-term health conditions

So if you're a kid who has asthma, diabetes, or another health problem, it's extra important that you get the flu vaccine. This is true too if you live with someone who has a health problem, or with a grandparent or a pregnant mom, so you can protect them.

Flu viruses usually cause the most illness during the colder months of the year. In the United States, flu season is from October to May. Flu vaccines are usually given before flu season starts. In the U.S., it's best to get it before the end of October. You can get a flu vaccine at the same time that you get other vaccines, like the COVID-19 vaccine.

Why Get a Flu Vaccine Every Year?

You might wonder why you have to get a flu vaccine every year. Here's why: There are lots of different flu viruses. Each year, researchers choose the three or four viruses most likely to cause trouble. The flu vaccine includes protection against those three or four, which can vary from year to year.

How Does the Flu Spread?

This virus gets around in little drops that spray out of an infected person's mouth and nose when they sneeze, cough, or even laugh. You can catch the flu from someone who has it if you breathe in some of those tiny flu-infected drops.

You also can catch the flu if those drops get on your hands and you touch your mouth or nose. No wonder people are always saying to cough or sneeze into your elbow, not your hands. And while you're at it, wash your hands well and often!

What If I Get the Flu?

If your doctor thinks you might have the flu, they might use a long cotton swab to get a sample of the gunk in your nose. Testing this sample in a lab can show if you have the flu.

But usually this isn't needed. Based on your symptoms and how you look, your doctor can usually tell if you have the flu, especially during times when a lot of flu is going around your town.

If your doctor says you have the flu, start taking these steps to feel better:

  • Rest in bed or on the couch.
  • Drink lots of liquids so you won't get dehydrated.
  • Take the medicine your mom or dad gives you to ease your fever, pain, and body aches.
  • Tell your mom or dad if you have trouble breathing, if you feel worse instead of better, or if you aren't peeing as much as usual. These are signs that you may need to see the doctor again.

Most of the time, kids with the flu feel better in about a week. Until they do, they have to stay home from school and take it easy.

We hope you're flu-free this year, but if you do get the flu, now you know what to do!

Medically reviewed by: Elana Pearl Ben-Joseph, MD
Date reviewed: September 2023