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The Flu Vaccine

Why Get the Flu Vaccine?

If you've ever had the flu, you know how bad it can make you feel. To help skip all that misery — as well as possible health problems from the flu — doctors recommend that all teens get a flu vaccine every year.

There are other good reasons too:

  • It's extra important for people with some medical conditions (like kidney disease, diabetes, HIV, heart problems, or asthma) to get a flu vaccine. They are more likely to have serious health problems (like pneumonia) when they get the flu.
  • Kids and teens who take aspirin regularly also need the flu vaccine. They're at risk for getting a serious condition called Reye syndrome if they get the flu.
  • Getting vaccinated protects the people around you. Because you're less likely to get the flu and pass it on, you help protect people who might get very ill from the flu — like babies, people with serious medical conditions, and the elderly.

When Should a Person Get Vaccinated?

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.

The best time to get a flu vaccine is before flu season starts. Getting it as soon as it's available, usually around September, gives the body time to build immunity. Your mom or dad can find out about vaccine availability from your doctor's office, or you can ask your school nurse.

Even if you can't get vaccinated right away, getting it later is better than not getting it at all. It's still flu season in January or February — even then it's not too late for you to get the flu vaccine. And getting a flu vaccine late in the season is especially important for people who travel. That's because the flu can be active around the globe from April to September.

What Are the Possible Side Effects of the Flu Vaccine?

Flu vaccines come in two forms, a shot and a nasal spray:

  • The flu shot usually is injected into the upper arm or thigh, depending on a person's age. It contains killed flu virus. It can cause soreness, redness, or swelling at the injection site. Rarely, it might cause a low fever or body aches.
  • The nasal spray flu vaccine contains weakened live flu viruses. So it may cause mild flu-like symptoms, such as a runny nose, wheezing, sore throat, vomiting, or tiredness. Like the shot, it can sometimes cause a low fever or body aches.

Both vaccine types cause the body to make antibodies to fight off infection by the live flu virus, and they work equally well. This flu season (2023–2024), get whichever vaccine your doctor recommends. People with weak immune systems or some health conditions (such as asthma) and pregnant women should not get the nasal spray vaccine.

The flu vaccine is very good at protecting against the flu, but it's not 100%. And it only works against some types of the virus. If a new flu type appears, a person who's had the vaccine may not be protected against it.

A few people who get the vaccine might get the flu. But the illness will be much milder and go away sooner than if they weren't vaccinated.

In the past, people with an egg allergy had to check with their doctor about whether the flu vaccine was OK for them because it's grown inside eggs. But health experts now say that the amount of egg protein in the vaccine is so tiny that it's safe even for kids with a severe egg allergy. People with egg allergies can now get the flu vaccine just like everyone else. They do not need to take any extra precautions.

What Else Should I Know?

  • Sometimes people feel faint after getting a shot. To prevent this, you can sit or lie down for 15 minutes right after the shot.
  • You can get the flu vaccine at the same time as the COVID-19 vaccine.

Reviewed by: Elana Pearl Ben-Joseph, MD
Date Reviewed: Sep 1, 2023

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