When Second Flu Shots Are Needed for Kids

Doctor applies bandage to preteen girl's arm following an immunization
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If your child is getting the seasonal flu shot for the first time, you can expect that they will also need a second shot a month later. This probably wasn't the standard when you were a kid, but it has been recommended since 2009.

The Advisory Committee on Immunization Practices recommends that all children who are age 6 months through 8 years old should get two doses of flu vaccine the first year that they are vaccinated against the flu. If your child had their first flu shot last year but only got a single shot, then this year, they should get a flu shot and a booster shot.

How It Works

The second flu shot is a booster dose to improve the effectiveness of the flu vaccine in children. The second dose is given at least 28 days after the first dose. That first dose stimulates the child's immune system, but it may not be enough to produce the level of antibodies needed for protection from the flu.

The second dose results in the child's immune system producing enough antibodies so they will be able to fight off influenza when exposed. If your child didn't receive the second dose, they likely have some protection against the flu, but it may not be enough.

Timing

Your child should have resistance to influenza two weeks after the second flu shot. Without the second dose, your child may not be protected against the flu.

Because it takes time, it is best to get the first dose as soon as the seasonal flu vaccine is available. This is usually in September each year. That will allow enough time to get the second dose before the flu season has reached high levels of influenza transmission in your community.

The flu season usually starts in October and reaches its highest level between December and February. You want to ensure your child is protected as thousands of children each year are hospitalized due to the flu, and, tragically, as many as 170 children die.

Flu Strains

A new strain of influenza is circulating in some years, such as the H1N1 swine flu in 2009. In those years, experts may recommend that all children under age 10 get two doses of the flu shot, so they have protection against this new strain. They may even issue a specific flu shot against the new strain, resulting in all children needing three or four flu shots.

Nasal FluMist

For healthy children at least 2 years old, the FluMist nasal spray flu vaccine can usually substitute for a flu shot. However, this is not true every year as it may not protect against the strains circulating in some years (such as the 2017-18 season). Ask your pediatrician whether it is recommended for use for the current year.

A Flu Shot Every Year

If your child had two flu shots last year, that protection was only for last year. This is because the strains of flu circulating this year may be different.

Each year, infectious disease experts formulate the flu shot to protect against the strains that they predict will be circulating. This means the vaccine can be different from year to year. Your child needs the current vaccine to be protected.

A Word From Verywell

Influenza is a serious disease that is far more dangerous for children than the common cold. Kids can be germ magnets, and your child will likely be exposed to influenza at daycare, school, or on the playground. While the flu shot can't guarantee protection, it is the best way to prevent getting sick from the flu.

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3 Sources
Verywell Family 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. Full and Partial Flu Vaccination Coverage in Young Children, Six Immunization Information System Sentinel Sites, 2013-14 through 2017-18. Updated November 8, 2018.

  2. Centers for Disease Control and Prevention. Influenza Vaccination: A Summary for Clinicians. Updated January 28, 2021.

  3. Centers for Disease Control and Prevention. Live Attenuated Influenza Vaccine [LAIV] (The Nasal Spray Flu Vaccine). Updated May 6, 2021.

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