Why Do Some Kids Need Two Flu Shots?

Flu vaccines are recommended for everyone. Because the influenza virus changes and mutates, these vaccines are necessary every year. Young kids are considered at "high risk" from the flu. They are more likely to become seriously ill or die if they get it than older children and adults. So it is even more important that they are vaccinated against this potentially deadly virus.

You may be surprised to learn when you take your young child for their flu vaccine, that they actually need two. Your healthcare provider should tell you if this is true for your child.

Boy getting shot
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Who Needs Two?

Children under age 8 who have never had a flu vaccine before will need two vaccines their first year. These two vaccinations must be separated by at least 28 days.

The first vaccine "primes" the body's immune system and the second helps the body develop antibodies to the influenza virus. Young children are less likely to have come into contact with the influenza virus so getting two is important to ensure they are protected. If your child has never had a flu vaccine before and she only gets one, it will not protect her against the flu. It takes two weeks after the second vaccination to develop immunity and protection against the flu virus. 

The two vaccine rule is true for both flu shots (injected flu vaccines) and the FluMist (nasal spray flu vaccine). Flu shots are approved for children over 6 months of age. FluMist is available for kids over age 2 without a history of wheezing or asthma and certain other conditions.

Check with your pediatrician for the recommendations for the current flu season. In some years, the use of the Live Attenuated Influenza Vaccines (LAIV), commonly called FluMist, was not recommended because it had been ineffective during the prior flu seasons.

What to Watch For

Many parents worry about the possible side effects of the flu vaccine. Or they believe inaccurate myths about the shot - like that it will give you the flu (it can't). 

The most common side effects that children experience after getting the flu shot are soreness at the injection site and a low-grade fever. If your child receives the FluMist, she may have a stuffy nose, sore throat or low-grade fever. She may feel more tired than normal but that shouldn't last longer than a day.

If your child develops symptoms of a severe allergic reaction after receiving a flu vaccine, seek medical attention immediately. These would include tongue or lip swelling, difficulty breathing, vomiting, and hives. If your child has a severe allergic reaction to a flu vaccine, she should not receive one in the future.

When to Have Your Child Vaccinated 

If your child needs two flu vaccines in one season, try to get them as early as possible. Flu vaccines are available in most places by September each year. Getting the first vaccine early in the fall will make it more likely that your child can get the second one before the flu is widespread in your community. 

However, if you find that it is later in the season and you have not yet had your child vaccinated, don't think it's too late. Any protection you can provide is better than none. Influenza is a serious disease that can be life-threatening to your child. 

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Children & Influenza (Flu).

  2. Centers for Disease Control and Prevention. Vaccine for Flu (Influenza).

  3. Centers for Disease Control and Prevention. Misconceptions about Seasonal Flu and Flu Vaccines.

By Kristina Duda, RN
Kristina Duda, BSN, RN, CPN, has been working in healthcare since 2002. She specializes in pediatrics and disease and infection prevention.