One dose or two?

That’s right, some kids actually need two doses of the flu vaccine to get the best protection – a priming dose and a booster dose.
How Many Doses of Flu Vaccines Do My Kids Need?
You child might need two doses of flu vaccine, separated by at least 4 weeks, if they are 8 years old or younger and:
- this is the first year that they are getting a flu vaccine, or
- they have not received two or more total doses of flu vaccine before
That second part is a little confusing.
That’s because the two doses do not have to have been in the same season or even in consecutive seasons. As long as a child has had at least 2 or more doses of flu vaccine in the past, then they only need one dose this year.
And even if they have never had a flu vaccine before, kids who are already 9 years old, only get one dose.
“Evidence from several studies indicates that children aged 6 months through 8 years require 2 doses of influenza vaccine administered a minimum of 4 weeks apart during their first season of vaccination for optimal protection”
Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season
Why do they get 2 doses?
“The first dose “primes” the immune system; the second dose provides immune protection.”
Study Looks at Flu Vaccine Dosing in Children
Because studies show that getting 2 doses of flu vaccine like this works best!
More on Flu Vaccine Doses for Kids
- MMWR – Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season
- Guide for Determining the Number of Doses of Influenza Vaccine to Give to Children Age 6 Months Through 8 Years
- CDC – Children & Influenza (Flu)
- Why Some Kids Need a Second Dose Of Flu Vaccine
- Study Looks at Flu Vaccine Dosing in Children
- Study: Varied prime-boost flu vaccine combos protect toddlers
- Study – Immunogenicity and reactogenicity of 1 versus 2 doses of trivalent inactivated influenza vaccine in vaccine-naive 5-8-year-old children.
- Study – Influenza vaccine effectiveness in healthy 6- to 21-month-old children during the 2003-2004 season.
- Study – Effectiveness of the 2003-2004 influenza vaccine among children 6 months to 8 years of age, with 1 vs 2 doses.
- Study – Vaccine effectiveness against laboratory-confirmed influenza in children 6 to 59 months of age during the 2003-2004 and 2004-2005 influenza seasons.
- Study – Influenza Vaccine Effectiveness for Fully and Partially Vaccinated Children 6 months to 8 Years Old during 2011–2012 and 2012–2013: The Importance of Two Priming Doses
- Study – Live and Inactivated Influenza Vaccines Induce Similar Humoral Responses, but Only Live Vaccines Induce Diverse T-Cell Responses in Young Children